Reboots happened a lot on the Nokia 770 (with its pathetic 64 MB of RAM). But not on the later Maemo devices.
The 770 initially had no swap space and the engineers learned their lesson from that.
However, the 770 used iOS/Android-style multitasking in 2005 where apps would be asked to save their state before getting killed by the OS to free up resources. It didn't help much. The device still ran out of memory too soon. The idea of that poor multitasking was dismissed eventually as it turned out that putting more RAM and some swap space into devices added a lot more to stability.