I think there is a mismatch between most commenters on HN and who is making purchasing decisions for something like Linear: it would the PGM/TPM org or leadership pushing it and they are touching the tool a lot more often. Even if a small speed up ultimately doesn't make a difference in productivity, the perceived snapiness makes it feel "better/more modern" than what they currently have.

That said, I really enjoy Linear (it reminds me a lot of buganizer at Google). The speed isn't something I notice much at all, it's more the workflow/features/feel.