I think people might be talking over each other a bit here. Here's my take on what's going on in this thread, and I hope I can be helpful to @marcb and anyone else wandering in looking for info
There's no doubt that Magic Online is a flawed program, but it gets the job done, and it's by far the most active spot for Vintage games online, especially if you're not already part of any smaller group of players. You won't find league games as readily as you can find standard matches on Arena, but as someone who played vintage for a decade when paper was your only option, it's night-and-day how accessible and easy it is to find a Vintage game on MTGO.
If you want to play against the best players, with prizes on the line, and you want to do this remotely (surely a bigger concern these days), MTGO is going to give you that opportunity like no other platform can.
I'll follow up on @AeonSovarius 's desire to play a few games before buying a collection though - the MTGO UI is a bit awkward, it takes some getting used to, and some people will never get used to it. The first league you play in, you will lose games because of a misclick, or because your turn-stops aren't set correctly, or because you don't know how to put something on the stack without passing priority, or because you played Mindbreak Trap and counter your own spells because you didn't know that the UI for playing Mindbreak Trap is fundamentally broken.
Beyond that, it's a different experience than paper in general. Everyone will be affected by this on different levels, but playing on MTGO is emotionally a different experience than playing in paper. Your opponents are meaner to you, the losses and wins hit you differently. Personally I find myself conceding Magic Online games MUCH more often than I concede games in paper. Situations that in person I might feel tension or excitement can feel like a slog on MTGO. I find myself asking the question "Do I really care if I win this game?" a lot more online. Some people don't feel any difference at all, and some people just cannot enjoy MTGO. There's really no way to know if this applies to you without playing yourself.
@80PercentBuffoon is absolutely right that a subset of MTGO players have formed an active and passionate community on the discord server he linked to. If you want to find people to chat with about Vintage and you don't have a group you're already doing that with, the Vintage Streaming Community discord is an awesome place to check out.
All that said, cockatrice and webcam matches are other great ways to enjoy vintage as a hobby from home. Of course the price is right (it's free). I own a set of power, but I prefer to play with (easily distinguishable) proxies, even over webcam.
If you're comparing Vintage Magic Online to other online games, the pricing model is pretty awful in terms of value-per-dollar, but if you compare it to other ways of playing magic, you're basically going to be able to play any number of Vintage decks forever, for the price of a single mid-tier paper Standard deck that won't be legal in three months. Obviously it's completely a personal decision whether the value is worth it for anyone. I own a Vintage MTGO collection and a Vintage cardboard collection but I don't have a ton of other financial priorities and I'm lucky enough that my career path happens to be a lucrative one.
Playing with voice chat over a video call gets me much closer to the feeling of actually being at a tournament than I had expected. There's no reason you couldn't set up a match over MTGO and use a voice call too, and you'd probably get about the same experience. Personally I prefer the usability of cockatrice over MTGO, though MTGO looks nicer. When you're talking with your opponent over voice chat via Cockatrice, you can shortcut all the things you shortcut in paper, you can move through phases without incessantly clicking pass-priority, you can't really misclick because you can just roll back mistakes. Compared to Cockatrice, MTGO can feel glacial. To be fair, neither is very usable and neither looks very good. I also suspect Cockatrice against an unknown opponent with no voice chat is the worst of both worlds, but I haven't done that.
Obviously there are massive limitations here that aren't true of MTGO. In theory you can find someone in a server looking for a Vintage game on Cockatrice but I don't think it happens that often. Basically you're going to have to find someone who wants to play with you some other way, and then arrange to meet online. Practically speaking, if you're not already part of a community that does this, it's not very likely to happen. There might be a public Discord server where people try to find opponents, but I don't know about it. I would love for people to use TMD to coordinate games, but no one does.
You're never going to see a "large, official" tournament run this way. WotC can't officially promote Cockatrice (though I suspect they don't really have a problem with it), and it's more or less impossible to stop people from cheating in a webcam match. Basically you need to treat a webcam match the same way you treat playtesting at a card shop - you play with people you don't think are going to cheat, and you don't cheat because if you do, what's the point? This is very maintainable when it comes to one-off matches or small tournaments among friends, but it's going to fall apart if there are big prizes on the line. Basically if you want to play in serious, large, official tournaments online, it's MTGO only. For me that isn't a deterrent, because the best matches of Vintage I've ever played weren't in serious, large, official tournaments. For me Vintage has always been a format about small, player run events with no WotC support. But I totally understand the draw of a Vintage Challenge.