TL;DR
using/generating energy always emits heat as waste and there is an upper limit of efficiency that we are not that far from. if that energy was generated via something that is not a natural heat gradient for the earth's surface there is a net increase of heat in the earth system simply by generating and using energy.
a lot of energy sources fall into this: fossil fuel, nuclear, geothermal, etc. two that don't are (certain types of) solar and wind, since their energy would eventually be dissipated onto earth's surface whether we intercept or not.
that waste heat is currently estimated to be ~2% of the heating power caused by global warming, so already significant. we essentially have an upper limit on sustainable energy usage on earth (and therefore an avg per person usage) or we will have Global Warming 2: Waste Heat Boogaloo.
yeah, I had a similar thought about curators, but in my mind, if the curators own a single self-contained platform, they will inevitably become corrupt. so if that's true, let there be many instances and individuals can choose what to trust.
I think a platform like this would be very different from lemmy or something because instances/communities/whatever would be internally incentivized to keep the quality of reviews high for their own sake (which others could benefit from too). maybe that manifests as heavily controlling sign ups or new members are able to post reviews but need to be approved in some way to have their reviews included in the overall instance stats. just spit balling, but I think mechanics that assist that will be very important.
being open source does guard the code, but I think the far more important part is the running platform and its data. I imagine any platform like this will want to own all of its data, so anyone setting up a new deploy would completely start from scratch. if nothing else, people would have to recreate their accounts and attempt to recreate their data. and if past attempts to get people to switch platforms is any indication, I think that would be very difficult.