The curse of early-and-good-enough systems. It's the same for bash and a few other things. Not enough pain points to replace them even though there's lots of better alternatives.
If you need something that will be supported for the next 20/30/50/100 years, you pick an already established product that is widely used and does not depend on any single organization. You can't rely on volunteer projects, as volunteers have no duty to maintain and support the product. And you can't rely on anything made by a single company, as companies lose interest and die all the time.
LaTeX's support is already problematic. Most people just don't use it in sufficient intensity to notice. We produce thousands of (mostly) custom written technical reports a year using LaTeX and there are all sorts of subtle issues cropping up. It's a distribution (edit: or at least texlive is) of many, many packages from many developers, and maintenance can be spotty and vary. Unlike some people would like to believe, stuff breaks all the time.
I'm not even going to comment on the fact that all of the following packages provide some sort of tabular feature: array, table, tabu, tabular, tabularx, longtable, supertabular, longtabu, xltabular, lxtable, booktabs, tabularray, ctable. Good luck figuring out which one does what you need and has the least side effects with everything else.
Also, while I'm not familiar with the internals of the LaTeX project, I keep reading the same names, most of which appear to be getting closer and closer to retirement. I wonder if suitable successors will pick up the task of maintaining LaTeX in the future.
LaTeX has always been like that. Random packages have never worked together properly, and submitting the manuscript in the format the publisher requires has always been a struggle. It's often easier to reinvent the wheel than to use a third-party package for some functionality.
The way I learned it, the best practice of using LaTeX has always been based on whitelisting. When you create documents for yourself, you establish a list of packages that work well together and stick to it. And if you expect documents from others, you provide a document class and a list of supported packages.
But despite all these shortcomings, LaTeX is widely supported. Both in the technical sense and in the social sense. Journals and similar entities not only accept but often except LaTeX documents.
Making tools libre as a matter of course and mailing people checks for bug finds just rings different than today's dominant paradigm of landing pages, conversion rates, social media tie-ins and for-profit non-profits...
My guessed probability that LaTex is free and maintained in 15 years: 99.9999%
My guessed probability that $OTHER_NEW_TOOL is free and maintained in 15 years: 5%