Many shops that "sell" GPL software (ie. the massive WordPress plugin and theme ecosystem) are actually selling support, convenient, secure(ish) updates, and go

Many shops that "sell" GPL software (ie. the massive WordPress plugin and theme ecosystem) are actually selling support, convenient, secure(ish) updates, and good karma. It's perfectly legit. You can find the sources for these items elsewhere on the web but the hassle and security implications just aren't worth it.