What is Riot's problem with Lissandra?

I know this will seem like a QQ thread (well, to be honest, partially it is), but I'd really like to know the reasoning behind her nerfs. In 6.17 Lissandra had 49% winrate according to champion.gg (which considers plat+ games). She was quite rare in ranked games and I don't think anyone considered her OP. She was played a bit in pro games, and correct me if I'm wrong, but I don't think she was too oppressive there. She's probably the shortest-ranged mage in the entire game and she doesn't have any shields in her kit, unlike many mages that are safer to play (due to much higher range - ( ).

I read the description in the patch:

However, her innate tankiness is also outclassing other burst mages, making her choice too easy: ult an enemy because she’s probably going to live anyway.

And to me it seems like bs. First, like I mentioned, she isn't really more tanky than Lux or Viktor. Even though Lux doesn't even need to be tanky, because she can snipe people from 10km away (btw, Lux received a buff in this patch, despite having higher winrate than Lissandra - that is just some twisted logic I can't comprehend). Second, to me her "innate tankiness" is far from enough to be able to engage and survive more than 2s close enough to the enemy team to be able to deal any damage. If I get so close to the enemy team (not to mention diving their backline), I usually die in less than 0.5s, often before I manage to use my ult and/or Zhonya. Yes, I know it's because I'm bad. I'm perfectly aware of that. But even bad players are sometimes useful to their team. To me, I can either stop playing my favourite champion altogether, or be useless in every game.

PS. Downvote this thread all you want, but at least be so kind to provide an explaination, please.