This is more of an issue than ever as new chips and 5g modems produce more heat, and the performance degrades. EVERY SINGLE FUCKING CASE is a thermal insulator, and even if it weren't, there would be a ton of thermal resistance in gap. This is why it would be vastly superior to simply have a phone that is toughened and doesn't need a case. There hasn't been a decent flagship tough phone since the Samsung S8 Active.

But your question is dumb. Phones still get better year after year wayyyy faster than cars. More than 1 year is reasonable, but definitely not a decade. Phones are also cheap. If you got a $200 phone every 2 years, you would have a way better phone than $1k phone every 5 years, and it costs a lot less than a car while providing immense value. Modern phones are amazing.