If it helps, you can create a party and then click "Make Private" and then you won't have to play with other people (you'll just be in a party of 1). I should really make that workflow easier though, I wouldn't expect a new player to figure that out.
Yup, I had to dig to find it. The "party" link didn't seem like the option I was looking for, until I saw the "private" option.
Also, I created a private party link, and figured out how to add an AI bot, after learning the controls.
The AI bot was still too strong, and beat me every time, so I need dumber bots, to have more fun up front. I sent the link to myself, and opened it up in multiple private windows, to learn the rules, against dummy sessions I created by invite.
But either way, maybe add a default practice button, that puts people in a private game, against a really weak AI, and you have your trainer option for new users.
I think a big, obvious training button sounds like a good idea. Especially for users that get killed in a competitive game with other people.
I switched over to Chrome, and even Safari, and it was better, so it seems like Webkit/Blink/V8 is the best browser scoped runtime, for some reason.