"Pay it forward" means to grant a favor or gift on a random person, in remembrance of one who did a favor for you before. The idea is to initiate a chain of favors and gifts to brighten the world in general.
It's a play on words though, by analogy with "Pay it back" which is returning a favor to one who did a favor for you first (like paying back a debt). In the case of large distros being heavily reliant on GPG and other upstream projects, I think the applicable term here is "pay it back".
Upstream developers helped out Debian, et al, and now Debian needs to pay those developers back. Arguably, by gifting their distros to the world at large, they're already "paying it forward".
It's a play on words though, by analogy with "Pay it back" which is returning a favor to one who did a favor for you first (like paying back a debt). In the case of large distros being heavily reliant on GPG and other upstream projects, I think the applicable term here is "pay it back".
Upstream developers helped out Debian, et al, and now Debian needs to pay those developers back. Arguably, by gifting their distros to the world at large, they're already "paying it forward".