Lol man your social trust way too low. These are all very valid concerns raised. But let me give a detailed comparison: First of all, this idea that small class size helps for career development is wrong because even if MIT has four times the students, it just factually has a much larger team for career development. I wouldn't index to this smaller class size things--important if you want a rec from a professor for a PhD. On top of that, you are always competing with everyone from every school and every program (graduate or undergraduate) for these jobs, what employers think is important. Finally, Princeton is famous for having a very heavy undergraduate focus as a school and the same cannot be said for MIT, which has a much more developed pipeline. One other thing is MIT has more industry lecturers and this can translate directly to jobs.
Again, none of this is to say you can't get a good job from both schools, in fact if you look at job placements from this year, you see they are similar: At MIT you have Blackstone, Citadel, Goldman, Morgan Stanley, at Princeton you have Balyasny, Goldman, Morgan Stanley, and Barclays. So for the top roles they are similar, but it is also just a fact that in terms of having a good reputation for being a very quantitative school in an engineering sense, MIT cannot be beat. Both schools have great ML courses. But I think that employers have some bias to the signal that MIT sends above almost any other school. Curriculum wise, look at the the core requirement for MIT Financial Mathematics or Adv Math Methods in Fin Engineering which is done in Matlab, Analytics of Finance, Advanced data analytics in Finance. Also, of course Princeton have well-designed CS courses--but it is also just a fact that the school has a more theoretical bent. It is an amazing school, but these things cannot be totally ignored since we are comparing two really top and similar programs.
What I say shouldn't be taken the wrong way. You cannot go wrong with either program. We are really all at the end of the day drawing at straws comparing two such elite places.