Most of the exotic and rare instructions are data that a linear disassembler plows through without knowing any better. 3dnow and via extensions aren't actually

Most of the exotic and rare instructions are data that a linear disassembler plows through without knowing any better. 3dnow and via extensions aren't actually emitted for common binaries, even if objdump claims they are there. Validating my own disassembler against objdumps output showed a lot of these outliers. A recursive disassembler is better at only attempting to disassemble code that actually appears in the code path, although then it misses things that are indirectly in the code sequence. It's an unsolved problem. You might consider rerunning your analysis with ghidra or Ida, but those aren't as easy to mass disassemble like objdump *.