@thamesynne >the LGPL only exists because there was some legal ambiguity as to whether linking to a dynamically-loaded library was derivation or not, which the LGPL resolves by explicitly saying "no, it isn't"
I suggest you actually read the LGPLv2.1: https://www.gnu.org/licenses/old-licenses/lgpl-2.1.html

The LGPLv2.1 notes that a linking with a dynamically loaded library makes a derivative work, but an exception is made to allow proprietary derivative works as long as the LGPLv2.1'd parts remain LGPLv2.1 and that users are permitted to reverse engineer the proprietary parts for debugging modifications.

Otherwise the LGPLv2.1 is the GPLv2 - you can choose to not use the exception and use only the GPLv2's terms instead.

>but in practice, one could take a GPL'd library, write a server around it that responds to incoming RPC requests by calling the exact functions and sending out their replies, release the code to that server, and use it to serve one's proprietary program with exactly the same results as an LGPL'd equivalent.
You'll end up with a chain of derivative works no matter how long you make that chain - a decision if doing such is copyright and contract infringement is really up to a court, but courts tend to see through circumvention attempts.