playing the game again after 18 months of no play my thoughts

So I started playing again aparently I did not lose too much skill as I placed gold 5 2 weeks ago and I am already gold 3. A lot of things stayed the same and I am able to do pretty good on a lot of things, but of course I still do not know the newer champions too well which hurts me a little bit. My thing is though some stuff is just absolutely insane such as walking through walls what is up with that it like hopping over walls is one thing, but these champs are flying like a rocket through the walls and I really do not think this is good game play. The mobility of newer champs is ridiculous although when I play my main Ekko not a problem, but when I played lux my backup champion the other night because Ekko was banned it was pure mayhem. I was fed I ended the game 14/11/9, but so many of those deaths were end game. Literally the Kayn on their team would go through a wall and 100 to 0 me and our ADC and there was nothing I mean nothing I could do about it. with squishy non mobile champions this is really a completely unfair disadvantage as what is the counter play for walking through walls how can you aim skill shots in the jungle when a champ can literally go anywhere they want because they are so mobile and not even stopped by walls. Maybe I am over reacting or there is some sort of counter play to this, but I am not aware can someone let me know?