Discounting this reason, and supposing it happened, then amazon could just turn up the dial and throw some resources at it. As things stand, they don't need to.
I have been an amazon affiliate for 10 years or more and, to be fair, they behave much better than any other affiliate program I have been involved with.
It takes a lot of work but if you have the resources practically all of it can be outsourced. What I do is learn as much as I can about each role that is needed, then I hire virtual assistants and train them to do that role. That helps keep costs down since you aren't hiring an "expert".
I'm growing a couple sites right now that I haven't written a single word for or taken a single photograph because I have some awesome writers and a photographer. I've also never posted a single article to Wordpress because, you guessed it, I have an awesome VA that I trained to do that for me. I even have a content manager (the highest paid role) who manages the writers and tells them pretty specifically what to write.
Also the majority of people do not block ads. This also depends on the niche though. Gaming and tech niches are usually low RPM unless you get targeted affiliate traffic (like you show up on Google for "Best Gaming Laptops of 2021")
As far as affiliate revenue, they are very likely to be making a purchase soon if they are looking at book reviews so if you can get them to click your Amazon affiliate link there will be fairly high conversion. The revenue per purchase probably is quite low due to the price and margins on a physical book (although I wonder what it looks like for Kindle books) but with enough traffic you can absolutely make it work. I can think of some interesting ways to get a lot of traffic with Pinterest as well in this niche.
This is a numbers game. Keep your costs low and your time involvement low and even if it is only making $2k/month that is good enough because you can have several sites at the same time.
Btw as far as needing a ton of traffic to make money well sometimes that is true to an extent. Recently I was looking at a website that was the most popular user-created website for a specific mobile game. It is generating $6k/month despite having the lowest RPM I've seen so far (only making around $2 per 1000 visitors). Despite this the hosting cost was only $50/mo and I bet I could get that down to $15/month with even better performance.
Side note - you get paid commissions on everything people buy for a certain time after clicking your affiliate link. People buy tons of stuff on Amazon so you'll get lots of revenue for non-book things too.
If you want more info on this type of business model go look at these site (I am not affiliated with them at all):
If you refer via a the books category and then someone buys from some other random category you get a much lower percentage. This has been a recent move and makes such tactics very unprofitable - for good reason too.