Small companies sure. Dark corners of a government hidden on the periphery who will not use such weapons until all else has failed, definitely... B... That's what I liked about he DS9 episode where Quark was selling arms to the smaller kingdoms in the Alpha Quadrant. There's a lot going on in the AQ other than just Humans vs Romulans.
But if almost everyone can make a treaty to stop metagenic weapons then maybe everyone got together and had a talk about how to ethically use a transporter... Which must put ideas in peoples heads, since the metreon cascade which is the weapon which finished the Talaxian/Harkonan war was basically a badly wired transporter.
I mean seriously, it's okay to use transporter scramblers to bobytrap Empok nor so that people explode rather than recombine into a person, but it's not okay to decompile a person with a transporter and then just shunt their matter stream straight into the ships Replicator biomatter reserve.