(But honestly tables suck bad time, I did wrote some table base hobby website back in 2009? or so and it wasn't nice (the experience, not the website which was quite fine). Sure basing a GUI on a grid is the best thing to do in many cases but tables are no grids. Grids are more flexible.)
(or it would if 5% of my users weren’t still using IE11, but that’s another story.)
You’re right, back in the day when everyone’s screen sizes were somewhat consistent, it worked, though still had many quirks.
It saddens me when Web sites assume they are in a full-screen window :(
The real issue with using <table> is semanticism, breaking DOM flow (sometimes creates issues for screen readers), and separation of concerns wrt data and style like you mentioned. Also, <table>s are hard to style over, like wtf is display: table-cell? Nobody seems to know.
But the number of times I see a colleague or fellow frontend cretin re-creating a tabular interface with a bunch of <div class="row"> etc... or wondering how to dynamically size the nested columns to fit the largest cell, I remind them: just use a table. Please.
You might notice that Hacker News layout uses <table>.
Now table layouts where quite a pain because they got very complex very fast. Flexbox and Grid are fine I guess, but I always found them a bit harder to understand than float and did not so much they offered that I needed.