CommonVoice is kind of the sound quality that you expect if random people talk into their headset microphone. So that's kind of the quality you need to work with to build a phone system for the general public.

LibriSpeech, on the other hand, is audiobooks read in a silent setting with a good microphone. And some speakers are even professional narrators. So that's the dataset to compare for for an office worker using it for dictation with high-quality equipment.

Also, Google is kinda famous for having the worst speech recognition of the enterprise offerings. (Microsoft's Azure STT has roughly half the error rate) Plus they tested Google's old model.

But the main point I'm trying to make is that even if it is "as good as Google", that a 20% word error rate is still pretty much unusable in practice.