Hybrids in D:OS 1 were certainly less powerful than pure builds, but the idea was to exchange power for versatility, a Hybrid could do more things than a pure character.
Which of course had two huge issues!
1) Mages are extremely versatile as it is and could cover anything they needed to do.
and
2) You took action economy damage as well
So in the end... Pure classes were in fact more versatile.
This isn't even including that a lot of the skill sets didn't combine too too well.
It always felt more like you were compensating, rather then making an impressive build.
Which is sad because I swear some spells were MADE for crossclass.