i fail to see what part of collective require gaining / hoarding / increasing planets / planet count...
collective are a bottom dwelling fighting race , you plunder planets , or farm on some carefully selected large ones ensuring your empires safety etc
your race pawnz hard in both combat / plunder & economy , especially considerimh its a free race , its weakness just like every race has them, is its handicaps when it comes to expanding the empires land mass for food production and climbing the ranks to compensate for it , while ensuring your empire isnt at risk too... ( unless your a pure plunder collective , obv yout not though )
you dont see collectives in the top ranks , its because they dont belong there , theres absolutely no point in them being there , theres no profit unless their plotting an UW / bored or have a agenda such as a fedwar / event ... even if they were to steal and plunder c3`s on a regular basis it would still be unprofitable for a collective to hang around in the top ranks , let alone extreemly turn / time / recource consuming...
and lets face it a guardian could climb to whatever power rating you managed to climb to in a day within an hour or two not even a fraction of the cash or minerals and kick you back down were you belong without suffering hardly any loss`s... but then hell most other empires probably could & would too... lthey arnt going to be scared of a counter atleast ^^