You're right that there are still thousands of examples of objects with identity and personality in all forms of modern art and design.
You're also right that modern design and architecture are shaped by changing missions, goals and standards (as well as changing fashions, material science, economic concerns, and maintenance and energy considerations since the 16th Century).
I don't think that was the twitter author's point, though. (I was quoting the author in the parent — it wasn't “my argument”.) They didn't say, “we should over-engineer structures even though material science has improved to the point that we no longer need to” or, “we should embellish things excessively even if the budget might be better allocated elsewhere”. They simply claimed that detail is linked to identity and personality; when there is less diverse detail in modern design there will be less diverse identity and personality.
This seems fair to me and it's easy to corroborate. Popular logos have converged around inoffensive icon + sans-serif font. New buildings are typically homogeneous unadorned concrete/steel boxes or glass towers or some mix of both. Popular hardware has converged toward a minimal glass slab. Sales websites feel like cookie-cutter versions of each other. These objects can all still be beautiful, but they can also lack personality.
The subtext in the author's thread was that it doesn't need to be this way. It is possible to meet modern goals and standards and also design to a budget, but be braver (the active, big-M Minimalism rather than the more cowardly small-m version). You can build “minimal” things that have details, identities and personalities. For example, Teenage Engineering[1] and Zaha Hadid's architectural firm[2] both inject their designs with detail and personality while following a minimalist/modernist style. This elevates them from the glass slab/box world of some of their peers, and it makes the products and environments more interesting to use and live in.
[1]: https://teenage.engineering/
[2]: https://www.re-thinkingthefuture.com/top-architects/a295-30-...