We already have a post like this.
`legacy' is probably a little dramatic when you're talking about programming code/routine.
Yes, I noticed that exist some post where the people show their favorite code. The reason for my post is the coronavirus, for example, lee mac, if this relevant die, will be a great punch to the entire world, then what lisp / code/ library might be shared for this guru to the world as a last wish?.
The person itself is the real value - the knowledge and the idea he shares,
so take your time to study LISP and participate on the forums because you are missing alot more than some libraries.
I feel honored for the ability to share ideas and questions with people like Lee Mac, VoVka, Stefan BMR, MP, MR, gile, ronjonp, Tharwat, BIGAL, dlanorh ... just to name a few.
And I really feel that I'm missing alot from the knowledge of people like BlackBox, alanjt, Peter, Fixo and other seemingly inactive users, because I never was in touch with them,
it were just the posts on the different forums by them that got my attention (the 'libraries' you reffer to).
Often there are cases where the OP can't actually code, or isn't being good enough - but shares great ideas in the form of request or just a discussion,
and with the participation of others the whole topic becomes gold.
Even if that same topic stays unaswered doesn't mean that its a waste.
On the other hand I have this friend that only collects 'stuff' (libraries) and does just that,
hence without the actual ideas and the knowledge of assembling some pragmatical algorithm for a end-program,
one becomes a 'collector' and nothing more - no ideas to share, no skills to share, just 'discovering' other people's hard work.