The purpose of a permissive license is to encourage proprietary derivatives that come with intellectual property restrictions, EULAs, SaaS with vendor lock-in,

The purpose of a permissive license is to encourage proprietary derivatives that come with intellectual property restrictions, EULAs, SaaS with vendor lock-in, etc. The purpose of a copyleft license is to encourage derivatives that don't come with such restrictions. Copyleft therefore helps reach a local maximum of freedom for everyone as a function of restrictions on redistribution. This is the fundamental idea behind copyleft that so many people seem to misunderstand whenever they say that MIT/ISC licenses are "more free" because they come with fewer obligations: copyleft licenses like the AGPL force a vendor to give up some power to improve freedoms for the wider community. Compliance is only hard if you want to control others' computing; the whole point of copyleft licenses is to oppose that.