I also love OCSP stapling but there are some limitations:
- webserver need to implement it
- admin need to enable it
- webserver need internet access
Maybe they saw with some telemetry that very few website actually enable OCSP stampling and decided to implement a fix that cover all certs and can really be deployed
Firefox Telemetry shows Beta 104 users encountered stapling on 13.95% of TLS handshakes. [1]
The stapling telemetry is no longer turned on in Release [2], and even if it were, you have to do special things to look at Release data, but some years back (~2018 maybe?) I remember Release stapling was substantially lower than the more tech-savvy Beta and Nightly populations. Which is pretty normal, as tech-oriented sites are more likely to turn on advanced features.
Maybe they saw with some telemetry that very few website actually enable OCSP stampling and decided to implement a fix that cover all certs and can really be deployed