Microsoft was also a dissenting voice against WebSQL. It was a team effort (because this is about standards), not just Mozilla's "fault".

SQLite is not a standard, and it would have been an IE6-level mistake to bake SQLite quirks and bugs into the web standard for the rest of time. (It doesn't matter that SQLite is open source, it's still a central source of failure that the web doesn't necessarily need in every browser for the rest of time.)

Just as "entirely" as the blame lies with those suggesting WebSQL not proposing something that meets the well-established and agreed on expectations for a web specification, and not fixing that issue when it was pointed out.