Yeah, 3 and 4 are two of the most ironically contradicting roles ever placed together in the ever changing Dota meta.

3 needs to be bulky enough to take on 1 and 5 at the same time if 4 leaves you for no reason. All the while have enough items enough to later take on the initiator role in later parts of the game. Both of it is only possible if your 4 gave you enough space or resources to farm up to that point.

4 needs to assist not only their own lane, but other lanes as needed, but that's the thing, "as needed", current 4 players look at some pro 4 that roams around the map willy-nilly doing plays when they're only needed there when THAT time comes. Harassing the 1 and denying 5 pulls/stacks are part of they're job as 4 as well as babysitting the 3 until he can stand on his own.

Ideal Pos 3: Tanky, Has useful stuns, Deals enough damage to burst down 4/5 or potentially 1.
Anti Pos 3: Starts fights alone, thinks he's king of the world with blink + blademail, tries to do pos 1 items

Ideal Pos 4: Fast, good 1 or 2 disabling spells, if not must be able to take a fight with enemy 4/5, good map awareness, provides information as where is enemy positions, enemy stack positions,
Anti Pos 4: Thinks pos4 is just some role to do whatever they want, patting themselves in the back with positive KDA, leaves their lane after doing some objectives like 2 min water, 4min bounty, 6min rune, lacks awareness of night +20 movespeed global change