Both Go and Jeff Dean's projects are meant for server-side work, so it is unsurprising that Mozilla is not a rival in this space.
However, it turns out they are heavily innovating in the same space as Go with their stunning work on Rust. Additionally, they are building world-class next-gen products with their work on Servo and Daala. Not to mention fantastic tools such as http://rr-project.org/.
I believe your assessment of Mozilla's engineering talent is inaccurate.
Well, you could say Servo is world class, but on what basis? Rust looks very nice but hardly anyone outside Mozilla is actually using in production as compared to Golang which has a very good adaptation in the community.
However, it turns out they are heavily innovating in the same space as Go with their stunning work on Rust. Additionally, they are building world-class next-gen products with their work on Servo and Daala. Not to mention fantastic tools such as http://rr-project.org/.
I believe your assessment of Mozilla's engineering talent is inaccurate.