I was about to say that I never encounter TLS errors while browsing, but that's not strictly true. There is one such website, and it's only because the webmaster had a stroke and can't maintain it currently. But apart from that rather sad story I can't relate to your issues at all.

I agree. I don't remember the last time I saw an expired cert, and it was probably an abandoned web site (which would eventually expire even with a 3-year certificate as well). At least with Let's Encrypt you have to automate it.