Are you a technician or an engineer? And as a follow up, what part of the vehicle do you engineer?
Because this sounds a lot like a case of a dentist seeing a lot of cavities and making conclusions that teeth are "bad tech".
I live in a climate that's in yearly flux from -20 to +35 C and EVs have been normal here for a long time(7+ years) with no major issues. What parameters and therefore regions does your statement cover? I'm sure you can't run an EV in Syberia(RU), but people with petrol cars there have to run them even parked to avoid freezing during the winter so there will always be extremes.
As for the commercial equation: BYD and Tesla don't seem to be fitting that narrative. So this is not a matter of a marketing mistake - but an overall execution on the failed manufacturers.