There’s someone out there who wants to build for PowerPC. At some point you have to say it’s a tiny piece of the market and making a few people spend $300 for old hardware is better than maintaining back compat forever.

I understand where you are coming from and commend you for trying to support your users (I'd do the same!), but I don't think Apple marketed Rosetta 2 as a permanent solution after the transition.

Another aspect is, a Mac stops getting software updates after ~7 years, and then the API level starts to drift between the latest macOS releases.

So, after 10 year mark, you can't get the latest versions of the applications already since the features developers use aren't available in the older macOS versions and you can't run the software anyway.

More issues generally arise from supporting/qualifying older OS versions than supporting specific architectures in my experience, so developers keep around older hardware or VMs for that purpose. In some other circumstances Rosetta may not be sufficient for testing older Intel hardware (one example is work on GPU)