> it's unethical to cross in copying a former employer's product (if you don't believe that, you can stop reading now, because no argument will convince you)
I've upvoted your comment for the value of your perspective and information about your own history with replit predating CodeAcademy, and I appreciate that lots of us feel protective of our ideas and the capacity to benefit from the work we put into executing on them.
But... "no argument will convince you?" While it's sometimes true that people hold positions they didn't reason themselves into and can't be reasoned out of, I've found "no argument will convince you" is often indicative of the fact that the speaker considers their position a prima facie reality, which is another way of saying they didn't reason themselves into it either, and therefore may also be underappreciating the merits of a countercase. Or, perhaps as common, they've abandoned the merits altogether and are attempting to narrate themselves or an audience through a lowering of status of those who disagree.
There are real questions about what a knowledge worker has a right to take with them after they leave, and you'd probably find lots of people are amenable to the idea that an employer has some legitimate claims. If it's true that this project "copied even unique, invisible aspects of Replit's architecture that I consider to be flaws" then maybe that might even persuade people if those don't look like natural decisions for the domain, appear to involve some novel problem solving, and/or weren't made public.
But the person on the other side of the argument:
(a) clearly didn't think they were doing anything they needed to hide from you
(b) has already outlined why they thought all their technical decisions were either not unique or influenced by things you'd made public when you made it clear you felt badly treated
(c) sure seemed to be making shows of good faith vs being met with threats of using capital to fund an aggressive legal response.
Those might be the reasons why many here are taking a critical posture (vs, say, reflexively siding with an open source project).
You may find you don't care if you can persuade those who disagree you. Sometimes that's a wise course. You may even exercise the privilege to take this to litigation. But if you really feel your opposition is in the wrong here and want to make a winning case either socially or legally then you're probably going to have to engage some of those points on a more compelling basis.