Why do some fonts have no metadata?

I'm curious to understand why some fonts seem to have no METADATA.pb?

```
(venv35) ubuntu@ip-10-0-0-196:~/tmp$ find . -type d '!' -exec test -e "{}/METADATA.pb" ';' -print
.
./fonts-master
./fonts-master/apache
./fonts-master/apache/opensanshebrew
./fonts-master/apache/opensanshebrewcondensed
./fonts-master/tools
./fonts-master/tools/encodings
./fonts-master/tools/encodings/GF Glyph Sets
./fonts-master/ofl
./fonts-master/ofl/seoulhangang
./fonts-master/ofl/seoulnamsanvertical
./fonts-master/ofl/tharlon
./fonts-master/ofl/alefhebrew
./fonts-master/ofl/jejugothic
./fonts-master/ofl/laosanspro
./fonts-master/ofl/laomuangdon
./fonts-master/ofl/aksarabaligalang
./fonts-master/ofl/jejuhallasan
./fonts-master/ofl/notosanstamil
./fonts-master/ofl/mavenprovfbeta
./fonts-master/ofl/rokkittvfbeta
./fonts-master/ofl/khyay
./fonts-master/ofl/myanmarsanspro
./fonts-master/ofl/nikukyu
./fonts-master/ofl/sawarabimincho
./fonts-master/ofl/nicomoji
./fonts-master/ofl/amstelvaralpha
./fonts-master/ofl/jejumyeongjo
./fonts-master/ofl/hannari
./fonts-master/ofl/seoulnamsan
./fonts-master/ofl/souliyo
./fonts-master/ofl/lemonadavfbeta
./fonts-master/ofl/sawarabigothic
./fonts-master/ofl/hanna
./fonts-master/ofl/roundedmplus1c
./fonts-master/ofl/laomuangkhong
./fonts-master/ofl/seoulhangangcondensed
./fonts-master/ofl/podkovavfbeta
./fonts-master/ofl/mplus1p
./fonts-master/ofl/kokoro
./fonts-master/ofl/decovaralpha
./fonts-master/ofl/cabinvfbeta
./fonts-master/ofl/kopubbatang
./fonts-master/ofl/archivovfbeta
./fonts-master/ofl/jomolhari
./fonts-master/ofl/seoulnamsancondensed
./fonts-master/ofl/faustinavfbeta
./fonts-master/ofl/lohitdevanagari
./fonts-master/ofl/asapvfbeta
./fonts-master/ufl
(venv35) ubuntu@ip-10-0-0-196:~/tmp$
```

Review the repository paths listed in the report and compare directories that contain METADATA.pb with those that do not. Start by examining the repository's metadata conventions and the named font directories; done means documenting the reason for the differences and identifying whether any metadata is missing unexpectedly.

Written by the indexing model from the issue text.