MongoDB/NoSQL is deployed and used at large scale by companies like Facebook, Ebay and many others. That's quite far from "no one is actually making that choice nowadays".
They didn't chose NoSQL, they were forced to. I'm fairly convinced they started with relational stores. If a company or product grows to a point where relational data doesn't work, that's a problem you want to have.
The mistake is either thinking you need to design for facebook scale from the beginning OR thinknig that you can cut time in a startup by not having to bother with those pesky schemas that just slow you down.
Yes, I agree that an key-value store that lets you do embarrassingly parallel reads and writes is useful for scaling, but has't it been said enough that You Are Not Google[1]?
[1] https://blog.bradfieldcs.com/you-are-not-google-84912cf44afb
Why not just directly `COPY` your log files to something like Redshift?
The "important" events for data science are still stored on postgres (i.e. logins for checking if a login was malicious)