I'd also be curious to know what features that Edge doesn't support. I know it doesn't do everything Chrome does, but I haven't run into any scenarios that Edge didn't support in a long time.

It's a pet peeve of mine that apps don't support Edge/Trident, Vivaldi, etc. It's easier to write cross-browser code than ever, but it seems like we're in the process of reverting back to the bad old days when IE6 was the only browser people supported, but it's Chrome now instead of IE.

IE6 was closed source and only ran on Windows... Chromium/Blink run cross platform, open source and already 2 forks in. There's some stark contrast, even if it's more of a mono-culture, it's nothing like the IE6 days, even if google does have more power/control than other stakeholders.

IE had a mac version, but it died due to lack of interest/support

The Mac version had a completely different, incompatible, renderer (which was actually better than the Windows one from a standards perspective) https://en.wikipedia.org/wiki/Tasman_(layout_engine)

IIRC, the mac version never got an IE6 release, it was 5.x...

It really is getting bad. I use Opera as my 'daily driver' for work, and I get warnings on sites at least weekly where the site will either complain like I'm using some dangerous outdated software, or just plain refuse to work, nevermind the fact that Opera actually uses regular old Blink. Present-day Opera is just a minor reskin of Chromium - and I think Vivaldi is Blink too, right?

People are literally doing User Agent Sniffing again, and even though these browsers carefully craft their UA string to pass naive checks, the sniffers are hacking around that and urging me to "Download Chrome" to use a website.

Notable Offenders: Google Hangouts, and banks. Not impressed, Google.

Has issue in not printing PDFs correctly. Namely changing text, swapping out fonts and other issues.

Yeah, IE needs odd custom CSS designed for accessibility, to make up for the mountains of missing CSS spec in it. And forget it if you use flex.