Idea is not to bundle by default for all, but to have an option so that builds may bundle what they want. Example "Google DocRepair" fonts that was first bundled was later nicely made optionally available with --with-docrepair-fonts option in bug 161941. Similar issue and main request here is with Source font families, unbundled in bug 136604 but shold rather be avalable with --with-source-fonts option. That font is rather usable and needed, also mentioned in bug 162872. I think that --disable-noto-font should also follow the same pattern and be renamed --with-noto-fonts.etc
Note: I would prefer also --with-fonts-fontname if all options could be the same like that, including the existing docrepair.