Bear with me, I'm going to start with an analogous situation, and then tie it to this one.
I play Go (the board game) at a fairly high level and have been participating in clubs and teaching Go for the better part of 15 years.
The simplest and easiest way to get better is to play the game a lot, hopefully against someone a little bit better than you are. You don't even have to spend a ton of time on it, just play and once you're done think about the moves you made and maybe a place or two where you could have done better.
There's several websites where you can make a free account and just click up button to say "hey, I'd like to play now!" and within minutes (or longer, this depends on the server and the level that you're playing at) you'll have a game you can get done in 30minutes.
It's crazy how hard it is to get people to play other people.
Most recently I've taught 5 people at my current workplace how to play. I've gotten them to play me, and, sometimes, each other. They've all made accounts on various sites to play, I've played them on those sites! They'll even sometimes play a robot on those sites (playing a bot isn't the best, but it is a little helpful).
Not a single one of them are willing to start a game with a stranger.
I'm sure nerves are part of it. But the reasoning I've heard time and time again, and not just with these 5, but with the dozens of people I've taught over the years, is some variation of "I don't want to waste their(my opponents) time".
They seriously feel like because they are still so new to the game, and still so unskilled that they would not be worth playing, that they would be "wasting" their opponent's time.
Take this to language learners, a lot of people do feel like as a beginner, talking to someone who is fluent is wasting the time of the fluent person. You're not paying them in the language exchange, you're just babbling to them like a 3 year old, a grown up who can't even carry on a whole conversation beyond "donde esta la biblioteca?".
You are right, language exchanges and just speaking with someone _is_ the best way to learn! It's super hard to break through the fear, embarrassment, and feelings of wasting another person's time with your own drivel.
Something like this, like the bots that play Go, are a way to bridge the gap.