But RMS and the FSF didn't, as far as I remember, oppose the DMCA! It's not because they were in favor of it, but because few people in the tech community outside of the DFC were paying attention.
If you look at the FSF's web site a few weeks after the DMCA became law, it talks about the fixing the (bad) Communications Decency Act, fixing (bad) software patents, and fixing (bad) crypto laws, but it doesn't even mention the DMCA: https://web.archive.org/web/19981206082742/http://www.fsf.or...
BTW, late 1998 wasn't exactly exclusively Usenet/phone coordination days. Slashdot with its Your Rights Online section had launched a year before, and Wired had already been publishing its Netizen section, including my contributions, for about three years. EFF had been around for almost 10 years, and there was VTW, CDT, EPIC, ACLU, etc. also in the mix. Even my Politech mailing list.
We were there. I was there. We were indeed outgunned. But also the politicians voting for the DMCA's "anti-circumvention" language never intended it to be wielded against farmers with John Deere tractors.