Larval isn't the only group leaving; Guzzle, Propane, SabreDAV and Doctrine have left too. Reading the mailing list and some other threads on /r/php there seem

Larval isn't the only group leaving; Guzzle, Propane, SabreDAV and Doctrine have left too. Reading the mailing list and some other threads on /r/php there seems to be an opinion that the FIG did excellent work creating the autoloader, code style, logging and HTTP Message standards however other recommendations such as caching massively expanded in scope with little community input. Also the signal to noise ratio on the mailing list was very high resulting in a laborious and off-putting read trying to catch up.