Yes but you need to remove the cable to ride the bike if it is run through a wheel. Usually it is more convenient to cable or lock the saddle to the frame in such a way that you can ride w/o removing the cable or chain. Also typically a chain or cable from seat to frame can be shorter than one run to a wheel.

Cables are quite esasily cut compared to chains IMO though either can be cut using a large enough bolt cutter. Cables can be more easily cut with diagonal cutters or smaller tools than chains. Using an old bicycle chain it can be disassembled using a chain tool.