Because Material is awful?
In their original iteration they had to do a study with 600 people to find out that text inputs should look like text inputs https://medium.com/google-design/the-evolution-of-material-d...
Their latest abomination has almost nothing aligned optically: https://twitter.com/dmitriid/status/1643607965935476737 When there are 5 elements, they follow 5 different guidelines: https://twitter.com/dmitriid/status/1643682248959328258
> That is OK, if you know the rules you can break them, but often they don't know the rules either
And that's the problem with what I call "dribbble-raised designers" ("designers" of Material UI included): they work for the designs to look nice in static screenshots on presentation pages without much scrutiny, and that's it.