It's definitely true that Macs last longer, and also last longer between reinstallations.

After a year or so, PCs tend to become horrendously overloaded, grinding and groaning on startup as 50 applications all start automatically loading and trying to download updates, bombarding the user with cascading dialog boxes, popups, security warnings, etc.

Macs are a lot more restrictive about what programmes are allowed to do - for most applications, to install them you stick them in your application folder, to uninstall them, you delete them. Easy. PC programmes have a nasty habit of leaving all sorts of traces in your system and not properly uninstalling, part of the reason why a Windows installation becomes unusable more quickly than a Mac one does.