Firefox was/is trying to be a top browser in global market share. The "core userbase" is irrelevant to this mission. You wouldn't really even talk about Chrome's "core userbase" because they aren't trying to make a niche community happy, they are trying to best serve their billions of users, something that the author of this piece clearly knows nothing about - eg, when your userbase is this large, the only meaningful form of feedback is statistical analysis. Telemetry is of course the best option but if you wanted to know what "people were saying" you wouldn't be operating at the level of reading individual posts, you'd be looking for trends on social media platforms.