integrated efficiency - how does it really work..

I can put new active skill gems with "connected" green or red and my damage skill have no improvement at all! same dps same "skill speed" same crit.

pob shows 3% dmg increase which is same as random one tiny dmg node in whole skill tree.

how did devs balanced it? is that really worth one tiny random dmg node on skill tree? this whole big ascendancy node?