You’re getting downvoted but I think despite the tone you are correct. 10 years ago corporate guidance on web dev was backwards compatibility going back several versions. Now it’s hardly any concern for anything more than 6 months old.
More than anything I think it’s because corporate IT has had to modernize due to security. Security now wants you to update constantly instead of running old vetted software. You also cannot demand user use an old version of a browser that still supports some old plugin. And as a vendor it’s not profitable to support people who maintain that mindset.
Also “update to the latest version” is the new “turn it off and back on again,” when it comes to basic IT help.
Chrome is evergreen, even on Android. Safari, after a bit of a fallow period, is updated fairly aggressively, and though it’s still coupled with OS updates, it’s no longer married to the annual x.0 releases.
Mind you, I still believe, and practice, you should write semantic HTML with progressive enhancement. But at the same time, I absolutely do not think you should go out of your way to test for some ancient version of Safari running on a first-generation iPad Pro—use basic webdev best practices, and don’t spend time worrying that container queries aren’t going to work for that sliver of the market.
Most people auto update their software or they don’t at all. What they don’t do is buy a brand new laptop as soon as it’s out. And the one they have is a cheap one from HP or Dell. To know their pain, try to use one of these.
I've got an iPad Air 2 running iOS 15.8. My user agent will surely tell you I'm only one or two major versions behind the "latest and greatest" but the hardware itself is a different story. On this device modern GitHub consistently crashes when displaying more than a few hundred lines of code. I've lost the ability to use a perfectly functioning device due to bloatware.
Because the people with money who are buying your products are all running the latest version of iOS. The ones on a 6 year old Android version are not spending anything therefor it isn't worth investing money in making sure it works for them.
Part of it was that users were terrible at updating browsers. You needed to support Internet Explorer 6, or cut off a third of your customers. It sucked.
Now every browser gets updates, automatically and aggressively. The only real outlier is Safari, but even that updates way quicker than older browsers used to.
More than anything I think it’s because corporate IT has had to modernize due to security. Security now wants you to update constantly instead of running old vetted software. You also cannot demand user use an old version of a browser that still supports some old plugin. And as a vendor it’s not profitable to support people who maintain that mindset.
Also “update to the latest version” is the new “turn it off and back on again,” when it comes to basic IT help.