Yes. Such things were in my recommendations. You could ensure stuff can always be traced to source (at transport level), filtered, and/or rate-limited. DDOS's get rate-limited automatically by ISP endpoint or middleboxes with costly penalties for this happening. Simultaneously, supply side starts offering all kinds of options to prevent that which are cheaper than being declared digital version of a public nuisance.

The Tier 1-3's mostly don't care since they're paid primarily to provide the line plus have regulators in their pockets. There's certainly work in these to reduce DDOS a bit for competitiveness but they avoid a simple solution like mine out of greed. ;)