m6.12xl are 48 vCPU systems. 25 million cores is a hilariously huge amount of compute to use to run a site of twitter size, which I guess does point to how much tech debt they have ignored over time.
Pretty sure Google hasn't used 'bitshift puzzle' interview questions for ~10y now. It really is just a meme thing from long ago. My interview there ~6y ago was basically the same as ones I've done at a handful of other companies
The problem here is really just general flaws in capitalism. The main thing I hate about ads is the broken corporate incentive -- companies want to earn as much as possible and the feedback loop of worse customer experience is weak.
So annoyingly while it is true that ads are a currently necessary part of funding the internet, it is also true that a perverse incentive exists to just keep hammering the $ button once you find a model that works. It is a good argument for why we probably should want to pay directly for content. Or y'know, just topple capitalism on account of it generating toxic localized optimizations literally everywhere.
Each ad serve is not worth that much to start with, facebooks CPMs are about $7-8, so they are getting $0.007 per serve with extensive targeting. The falloff is something around 10x+ for completely non targeted ads which for most sites push them below the level of economic feasibility.
This is also why if you stumble into some parts of the web, they vomit out a billion ads per page to try and compensate.
Really the problem is that there is a tremendous gap between the costs to serve content and users willingness to pay (either directly or via any indirect method). It is a tremendously deep hole we've built with freemium models that will probably require some level of societal agreement to dig back out of.
If you remove pay models, a vast majority of the internet will just disappear. (I think you) in a previous comment mention that it is 'cheap' to run a site, which is generally true on a per user basis for primarily text sites. But cheap != free.
I see it often, but it is honestly the most laughably selfish opinion to believe that one should be entitled to the internet as it exists today, but also not pay directly or indirectly to be able to use those services.