Enjoying a game, video, or music is different than enjoying the underlying means of delivery.

Do people love Javascript and HTML5, or do they like streaming entertainment?

Do gamers love Unity, or do they love playing fun games, some of which are made with Unity?

I played games on every Windows from 3.1 and up (and MS-DOS before that), but I'm not pining for the days of Windows ME despite how much fun I had on that machine.

People used Internet Explorer to run all their Flash entertainment, but nobody is arguing that IE was loved even though it was part of the flash stack for a huge majority of users.

Notably, Flash is dead, and no one is arguing that we bring it back.

If I never have to sit through a flash loading bar gating an HTML website with a completely unnecessary splash page, you won't find me mourning. (yung'uns: this was a thing. If you wanted to go see a website sometimes you had to sit for a while so a dumb flash animation would show and you could click through to the actual HTML content. Jobs did you a favour)

You're completely (and I think intentionally) missing that flash enabled people to easily create those things... and that creativity and ease of use still hasn't been replicated (your example of Unity - doesn't come close to the ease)

People loved flash for what flash was good for (creative toys) they disliked flash when certain sites started making it the core of the navigation etc.

When people are nostalgic for flash it's for finding random toys from other people who weren't "IT people".