Approximate yearly sales of desktop PCs worldwide (all kinds) are 200 million per year... I can't find 5 year refresh cycles on any HP, Dell, etc. desktops or laptops.
They tend to refresh in line with corporate cycles, i.e. 18 month to 3 years, from what I see.
The main reason to buy a new phone these days surely is "the old one broke". Being with us all the time. The planned obsolence - unreplaceable battery, glued screen, glassback etc mean phones break all the time.
PCs stand still, even laptops tend be mostly stationary. No wonder my work laptop is now 6 years old and I feel no urge to request upgrade.
People drop their smartphones more often than their desktops.
But I expect cheaper devices to take more share, since the "high-end" won't give you much benefits over them. My 120 EUR Xiaomi already offers amazing cost performance compared to most other Androids.
They tend to refresh in line with corporate cycles, i.e. 18 month to 3 years, from what I see.