A max size reactor in minecraft consists of 50000 Tileentities and it only produces a few million RF/t enough to power a handful of max tier void miners. Thousands isn't exactly impressive.
Well we had a max size reactor powering our excavators so I guess we had those entities too. I didn't realise it took so many entities to run. Not to mention the hundreds of other pieces in our worlds automation puzzle and it was all spread out quite far apart, with chunk loaders maintaining the networks presence. Things were routed, crushed, smelted, crafted and eventually stored or utilized, all automatically.