I think these questions are tough to answer in game development especially. People are still making games for downright ancient systems and tech.
I've helped ship AAA games on forks of engines over a decade old (in the 2010s we could still find fossilized comments from the 90s). And I think we all have a chunk of our codebase somewhere that we now know is horribly outdated but just not bad enough to be critical to replace just yet. It happens. It might not be what we'd call "best practice" but if a thing works, it works.
So, I think the answer to all of these questions ends up being "yes" in the sense of "nobody will stop you" but also "no" in the sense of "if you decided to ask, you probably already know there are 'better'/more popular options you should probably use today" without a lot of conclusive evidence we can present either way.
(Sure, Flash support is officially ending, but sufficiently-motivated players still dig out and maintain their original NES systems, so is a lack of support an absolute deal-breaker? Seems like that will vary based on a developer's opinions and aims)
So, I have a hard time envisioning what a high-quality, useful answer to this type of question will be. Most I've seen boil down to "I wouldn't recommend it" which the asker probably already knew, else they wouldn't have asked in the first place.
I don't think the site or its users gain from considering these questions on-topic.