It's so funny for me to read these statements from the philistines.
As I have written many times before, if there is a dead end in silicon, they will sell you "rhinestones". Now you are discussing "rhinestones", since there is essentially nothing more to discuss in the smartphone industry. New products are becoming more and more boring, and the increase in performance per 1W of consumption is less and less with each new technical process, which is becoming more and more difficult for chipmakers.
The author writes from the position of an amateur that does not paint the site.
Plastic has poor thermal conductivity (everything inside overheats faster), but is radio transparent and shock-resistant. But it resists scratches not good.
The metal is extremely durable (of course not pure aluminum), but heavier, an excellent heat exchanger for removing heat from the inside (but also bringing it from outside to inside) and the key drawback is that it is not completely transparent to radio waves. Therefore, completely metal smartphone cases do not exist in nature - there are plastic inserts everywhere, which automatically spoil the appearance for the bourgeoisie, for whom "rhinestones" are more important than the performance and efficiency of antennas.
Glass as a whole is radio-transparent, it protects rhinestone lovers well from scratches for subsequent resale of their junk at a flea market, but it is extremely fragile. And also not a very good heat exchanger.
Today there is no ideal case for a smartphone so that it is 100% radio transparent to antennas, an excellent heat sink for dissipating heat to the case, and at the same time extremely durable against shocks and scratches.