IR bottom heaters are usually not strong enough for reballing. They’re for boards that are hard to solder, because there’s a lot of copper or a heatsink for example.
The bottom heater preheats the whole board, not to soldering temperatures but enough to make soldering a lot easier.
The same worries exist here too though. The blood bank isn’t allowed to pay you for your plasma, but it’s absolutely a for-profit organisation that runs on selling your plasma to pharmaceutical companies.
I still believe it’s a good thing to donate, but sometimes it feels a little icky that there’s also a businessmodel around it