I didn't know either, so I started searching around. Just typing "limited run games" in DDG the suggested search that pops up is "limited run games controversy", which is never a good sign. Looks like there have been a few issues and even settlements.
Theres a lot of reasons.
One is that their CEO is an unhinged ass. If you complain about something or return a defective product the ban you from buying form them ever again.
And that they are basically scalpers. the "Limited" in theire name is an outright lie as they usually print a lot more copies of "rare single run games" and then sell them on ebay for an extra profit.
just your general allround asshole business.
You can find more detail information on youtube