Why can Talon have all the strengths of old Rengar? [Discussion]

But yet still remain un-touched. (To be clear, This is NOT a complaint thread. This is a comparison between the two assassins and the purpose of this post is to create a valid discussion and to receive feedback)

Old Rengar's Q could crit and apply on towers.That was proven to be too powerful, so it was removed. Talon's Q can crit and apply on towers. Old Rengar's E is a targeted slow, Talons E is a targeted slow that functions as an engage/blink to any target and allows him to set up his combo and juke people out. Old Rengar's Ult gave him a huge speed boost and the potential for escape or engage on an opponent. Talon's Ult does the same while adding damage to his kit and burst.

Now, They both have insane damage, mobility and burst, but why is one less acceptable then the other? Why can one exist while the other be taken away? I feel that it's because of timing and the meta. If I can recall, back when Rengar was reworked into what he is now, Burst mages were taking the stage and were too powerful at the time for talon to handle, meanwhile Rengar at the time was a dominant pick with insane pick potential and burst against other junglers at the time. So Riot did the good thing and reworked him and made him relatively balanced but can still snowball, good job on riot for keeping his identity.

Fast forward to now and talon is destroying his squishy opponents and bruisers in solo Queue and is snowballing extremely hard. With the tank meta that's going on right now I still feel talon is a great pick because of his immense damage, mobility, bleed and stealth. Since his average build contains every armour pen item tanks aren't a huge issue anymore and because armour pen still helps a ton against the low armour squishy ADC's, supports and mids running around, he can jump to the backline once a teamfight breaks out and burst them before any action could really be made. This was the same issue that Rengar had, but yet a talon nerf/rework hasn't been talked about. Does he even need one? I'm not fully sure myself but I do know he's a very strong champion at the moment and could use some toning down imo.

Feedback is appreciated and Tell me your thoughts about this situation and what you think about both of them.