Well let's take three examples: WoW, EvE and Runescape.
in runescape, you cast a spell to heal someone.
In WoW, you cast a spell to heal someone.
In eve, you run repair cycles to repair someone.
In gw2 if you're a water elementalist, you have 0 direct heals basically, and most of your healing capability is either very light or on cooldown. It's got some similarities with Dota2. If you're a druid, you have to have an enemy involved to use your basic heal usable, you can't just beam the ally directly.
In WoW and EvE, stealth is a thing you do, it's permanent. in GW2, it's more of an in-combat thing (by the way, I'm not complaining about this)
The ranger's first unlock with sword (aside from 1) is hornet sting, which is actually a gtfo button.
Point is, a lot of tactics in gw2 are very indirect and are seemingly designed for combination tactics, and I don't think that appeals to people immediately. I think the spirit utilities for ranger are the best ex...