If Magma_Axis gave me incorrect information that's not my fault and that doesn't make this a good design decision just because it's equally bad on all platforms.
Even if you say it's an intentional part of the system that is belied by the fact that the AI controlled characters can use any number of abilities.
This is actually a fair point. However my thoughts on the subject are hopefully in the future, the will be able to incorporate cross-platform multi-player. That is honestly the only reason I can see for the restriction.
The other point of dismay I have with the restriction is, it restricts some classes more than others. A good example would be tempest. Needing the 3 slots for your flasks really limits the other spells you can take. In addition, 1 focus ability. Which brings it down to 4 active abilities. As a Rogue on nightmare I'm pretty much forced to have at least 1 escape method, bringing it down to 3.
I have alot more than 3 Damage Dealing abilities I would like to use, thanks 