Olaf, Trynda and Illaoi will simply outtrade him everytime, and while the first deal more dmg than him in early game unlike Illaoi, the Kraken priestess can simply push him under tower and her healing potential and her all ins will simply destroy urgot.
Urgot can't also push properly without running out of mana pre lvl 9, he can't really poke you down with Q (which is currenly maxed last and cost like 80 mana wtf) and he has to move in a specific way to proc his passive, which makes it even easier for skillshot based champ to land their abilities.
You can also ult during his ult with Olaf, Trynd, Ekko or you can cancel his ult with Fiora W, Kled Passive.
You can also cancel his ult if a Braum uses his shield in front of you or if you have a qss...
Since he has really bad matchup againist Trynd, Olaf, Fiora and even Jax if he even manages to get a kill, after 2 years of Urgot I can really say that he sucks if he's played from behind.
You should also notice that unlike many other top laners he doesn't build sustain AT ALL and he will have to recall way more often than anyone if he's low, he doesn't build tiamat nor he has any from of sustain in his kit.
TL;DR His Ult is countered by one item, he has no sustain, his e is predictable, his ult has a cast animation and you can dodge it or flash out from his range, and if he's trying to escape when he's pushing and he's using e, remembering that his e has a casting animation: just go in front of him and he will throw you back, and he won't escape. He also sucks a lot if he loses the lane.
He's definitely a best when he has a lead but unlike Jax,Trynda,Fiora etc...he's not a super carry, if your bot feeds and the enemy adc has your same kills, if he's smart you won't have the same utility of one of the champ aboves, since they can always kill you with no mana just by using autos and chasing you down, Urgot just can't.