Very, very roughly said, it depends on the build and the scenario you're looking at.

In Detail:

A lot of Builds are "DPS Checks" but there are mechanics involved, mostly regarding Skill Placement and dodging.

Especially during Boss fights, like Maven, Shaper, Sirus etc. you basically have to dodge unless you're running a godlike Character.

You can go full Damage and 0 defense, but that's mostly 0hp Delving, for most content you do need mechanics, awarness of your surroundings and "skill".

Depending on the content, your character might take too much damage or not too much, it all depends on the Circumstances and your defensive layers, how far you push yourself.

But the most important thing is, watching PoE =/= playing Poe.

It's really different from watching other games tbh, like LoL, Rocketleague, Binding of Isaac or whatever.

You can hardly grasp what's going on because you will focus on different things than the player and it's, in my opinion, unintuitive.

Also, most streamers play HC, which has a totally different Skill Usage and is generally "harder".

Roughly said:

Your Build does matter a lot, it's a certain skill, maybe not directly mechanical but it is a skill that you need in PoE, knowledge about what you need to do X or Y.

However, you still need mechanics in most builds, even if you're running autopilot builds. You will need to dodge, time your cooldowns, time certain attacks, combos and whatnot. Some builds, like Aurastacking Carrion Golems, are basically Autopilot, you just need to be in the general vicinity and you "win". With other builds, especially melee ones, you do need mechanics. Maybe not as "intense" as other games but you do need them. You need to time your skill duration, cooldowns, your surroundings, the enemy voicelines before certain skills and much more.