Yes, persistence is an additional expense in an exploit and fairly difficult to achieve on an iPhone. The idea with rebooting is that any malware living in memory will be cleared out and the attacker will have to throw the exploit again. Throwing the exploit again carries risk in getting it burnt and iPhone exploits are in the $1m - $2m range.
Given how we generally only reboot our phones for system updates, this is good practice.
Like if someone is determined to spend that amount of moola to spy on you personally, you’re a different category of person than the normal joe tho?
If an exploit is soon to be burnt/patched anyway, it can be used less carefully before expiration.
Hence Apple’s recent change to critical security update rollouts.