I'm a little more skeptical that this is "AI is big so it is worse" issue. Yes, AI is big in scale, but this has been the case for almost every popular free service. They either start:
reply- charging (news / journalist services)
- gate-keeping (X forcing log-ins)
- enshittifying (lots of ads and degraded service)
The fact that the way back machine is incredibly useful but most people didn't know about it or use it very much doesn't change the fact that it has basically become very popular... only with LLM agents rather than humans. Ads alone aren't enough to support human traffic for many sites with human traffic.