I'm not a programmer per se myself, I run my own Linux server and dabble with vue and other stuff, it's definitely been beneficial to me as a designer. Having tech knowledge, especially on the stack used, you get a good idea of what's possible to even do and where design starts to be a hindrance to the building of a product. It has helped me communicate with the developers and while it doesn't help me design, it still is beneficial to the product as a whole.
I don't think that designers should have to know development well enough to be able to build the whole product, but the more you know, the better it is.
This is pretty much the only advice I’d ever give to a designer. Knowing what’s possible technically, and knowing which of those possible things is a worthwhile ask makes you a more well-rounded technical product designer. That type of designer is much more valuable than the ‘well this is the design’ sticklers.
I don't think that designers should have to know development well enough to be able to build the whole product, but the more you know, the better it is.