For APCSA students, especially those who can take more CS courses before/after the APCSA exam course... these are high school level students. There's no reason why they can't be using a real IDE (e.g. Eclipse, or whatever you like), learning Java in a terminal, and learn to write real GUIs (e.g. Swing, or whatever you like) [1].
Yeah I know... Java, Swing, Eclipse... Look, it's AP CS A. Java is the language of instruction. No choice. But we can make the best of it. Students can learn using real tools.
In high school wood shop class, they teach what the pros use, more or less. Real hammers. Real drill presses.
That's not to say Repl.it is purely a toy tool. Of course you can make real things using non-pro tools too, ikea screwdrivers, dollar store saws, etc. But it depends on your teaching philosophy, goals, and resources. Some high school students are a few years away from working, coding, in industry --- why not learn real IDEs if it's available?
You're right, there's definitely a use case for Repl.it. Chromebooks... I'm sorry for your situation. Even a cheap laptop with Windows or Linux nowadays is enough to learn Java with Netbeans and the command line. If my class all had chromebooks, I'd probably jump on REpl.it too.
But if students have a non-locked-down OS, seems to me learning the real deal is better for the student. It's not just the IDE and coding in it. It's the entire ecosystem students get to be exposed to. Get stuck on something, jump in the command line. Learn git in bash. Play with maven. It's a rich, real, authentic environment to learn in. Stuck in the browser means only getting what the web site provides.
But that's old school thinking. I suspect the world of primary and secondary CS education will move more and more into REpl.it style web based tools. Here's why:
Everything's getting locked down, and people are busy.
If a student comes and says they have trouble installing Java in Windows, it's easier to just say... go to ReplIt.
If a school board is downsizing / rightsizing / cloud-ifying their I.T., they might say they won't allow/support/install Eclipse on school PCs anymore, because it takes too much technician time to support it, or it opens up security issues to allow arbitrary code from students to run, or they want to replace everything with Chromebooks, or just do it in the cloud...whatever. What's a teacher to do? Replit.
Students comes with a Mac, all locked down, has trouble even running example or utility programs from the teacher because of notarization? Replit.
Student has no desktop/laptop. School does'nt have a chromebook to lend out. But probably student still has a mobile device! Replit.
As coding education becomes more widespread, like math before it, more and more classes will be taught by teachers who are not experts in coding, possibly not even by a hobbyist coder, maybe not even by someone who likes code. It'll be taught by an English / math/ bio / P.E. teacher who needs a class to round out their 1.0 FTE. Maybe supported by an expert CS teacher, maybe, but at some point everyone's busy. So much easier to just use repl.it. Gives students some activities to do.
And how's the social teacher who's never seen a terminal supposed to help troubleshoot classpath problems in Java on a student's computer? or on a school computer they have no admin access to because... I.T.? That teacher may be very capable, but who has the time anyway? Replit with constrained templates and projects will be very very helpful.
Sorry this is so long...
tldr. If students have a non-locked-down OS, seems to me learning the real deal is better for the student. But due to everything getting locked down, economic reasons, and teachers/people/technicians being just too busy, the trend in primary/secondary CS education will be towards more web based platforms... because it's better for the teachers/administrators/I.T./wallet.