That’s the entire point of those kinds of interviews. It’s a strong filter for “recent graduate” while maintaining plausible deniability for ageism. It has a secondary effect of filtering for “willing to do unpaid overtime”.
I fear it is like chess, the cognitive decline starts to become noticable in the mid 40s and only gets worse from then on.
There are a few exceptions like Korchnoi was in chess so there must be Fabrice Bellards and Bill Joys who would be able to keep up.
Still looking at completion times for Advent of Code made me feel old.
In my practical experience I find that to get the "aptitude" requires a lot of effort put in it. It definitely would vary depending on the person and his experiences but practicing it is very important to go forward.
They are a test of how recently you crammed for your CS finals, that’s all.
Which, to some extent, makes sense. You're basically filtering out people who won't put in the effort to get the job. Whether or not those who put in the extra effort are actually going to be better employees is a different decision.
To your larger point, data structures and algorithms are popular in interviews for the same reason Project Euler is popular - it is very easy to ask a well defined, but interesting question about core CS or math.
As is, it's more like advertising for python, then surprise java.
But those kinds of questions make zero sense and have zero value if the job is actually implementing CRUD apps in a high level language. You might as well quiz candidates on their assembly language skills too, for a Python job...
So there is obviously an ulterior motive.
People in their 20s and 30s now will regret not stamping out ageism when they hit their 40s and 50s, as they inevitably will
The problem is, everyone in their 20s and 30s assumes they'll be gazillionaires by the time they're 40, because of course they're brilliant and hard work always pays off! Ageism is only a factor if you're not smart enough to make a billion by the time you're facing it.
Unfortunately then the victims of ageism now will find that cold comfort in the future.