Well, the reapers did admit they wanted civilizations to develop along their planned path - harvesting cycles, the "good" benefits derived are there to entice space-faring nations to not go astray from the grand plan
Another point, it is interesting that reaper tech can only survive in an ending where the reapers are allowed to physically exist
They are tied.
People use stuff like Thanix cannons and such as examples of 'Reaper Tech'. Technically.. it isn't. It's tech at the level of Reapers, but not Da Reapah Tech.
Reaper Tech is anything that involves the Reapers' as intelligent entities really. Anything with indoctrination, the Reaper plan, huskification, etc. All the stuff that advances the Reapers as entities, up to being directly connected to them.
The history with Reaper Tech is that if you associate with it at ALL, you'll be manipulated to want more and more of it, to the point of eventual submission to the Reapers in some way.
You want those Relays? Well, you've opening yourself to the Harvest.
You want those nanite improvements? Well, you're opening yourself up to Reaper hacking and adoption of their methodology (becoming like them).
You want those artifacts? Well, you're opening yourself up to communication with Reapers and Indoctrination of your mind.
You want those Reapers? Well, you'll eventually want to make your own, and/or be part of one. Grats.
The Reaper 'Order' is overwhelming, and too much for an at least typical mind. They cover so many bases, so even picking up *some* Reaper tech opens you up for seeking more and more of it.