"To a certain degree"? Either they can keep organic civilizations under a chosen technological limit, or they can't. If they can't, they're toast, since sooner or later some society will surpass their tech. If they can, they can prevent any particular technology from being developed
Yeah, this one could kinda work. It's not consistent with actually exterminating a lot of species, but this could be worked around easily enough, if it turned out that most of the time they simply bust species back to pre-agricultural conditions on their home planets. (The Protheans would be a rare exception that the Reapers had determined to have no further evolutionary potential, at which point they were repurposed into Collectors.) But the problem, again, is that letting a species develop starflight is counterproductive
I see your point, but there's a difference between keeping comparitively simple organic technology or even reaper technology equivalents at bay. Those would require a huge and noticeable build up, that the reapers can stop, when they choose to.
Whereas developing the god AI could be, presumably, done on a single planet or a large enough ship ship hidden in trillions of places. It would then either be so powerfull that it mcguyvered a reaper killing device then and there or slink out the backdoor, travel to the next galaxy and having no moral inhibitions, conquer it, build whatever it needs to beat the reapers and return and wipe everything out.
Or maybe it's just being developed in that next galaxy.
In any case, being able to slap down the organics in this galaxy, due to numbers and/or technology is not sufficient to prevent the god ai from being created here or anywhere else within reach.
PS: Actually, the leviathans could have beaten the reapers billions of years ago, if they had programmed a simple ai to go to andromeda and build enough autonomous ships to kill the reapers. If the reapers are only limited to the milky way that is.
No, letting a species develop starflight is not necessarily counter-productive.
If your ressource is sentient organics, more is better, that means it's preferable they spread out, rather then being limited to their homesystem.
It's a gamble, because starflight means the ability to fight back, which presumably hasn't been a problem in 2 billion years.
However, given that there is a limit on ressources and you want to stretch them out, you also cannot let the sapient organics, consume too many ressources.
It's like farming, you want enough food not to starve, but you also don't want to overfarm.