The For network is slow compared to the modern web or interconnected AS.

Tor has scraping and DDOS concerns just like the regular web does. Heck I would argue that it has a bigger threat of attack mainly due to how isolated it is and how some might want to kill competition or make certain information inaccessible.

Tor and darknet markets have solutions. They don't use a CDN or a solution like cloudflare, but rather they implement openly accessible tools to help block these threats. Tor has a proof of work based method that helps increase the cost of attack. Open source capcha tools exist as well that do a great job at helping reduce the flood of traffic.