It was a selling point back then and the reason for a fork. Bram didn’t want to add async tech into Vim, cause async enabled various parallel-to-you visual activities. Neovim forked and did async+lua on its own terms. Vim later added async functionality, and I think it was the best outcome. Vimers still got shy LSPs and Neovimers got whatever they dreamed about in their separate emvironment. Good fork.
Things may have settled since then, maybe that’s why you think that this phrase looks odd.
Async is only a performance detail and using a degorary term as "pop-blink IDE" to refer to the choice to include async is wrong.
I've been using Neovim since it forked and it has always offered a Vim-like experience, it's just that Neovim has given you more options.
Maybe that's why some think it's too "blinky" as it's possible to turn it into a blinky IDE if you really want to because it's more capable (and some do).
What were these options? Something must have been very special to make a fork and not just a set of plugins. What was it, in terms of end-user features?
The feature I migrated for was async update and installation of plugins, and I used Neovim exactly as I used Vim a long time after that.
It's just in recent years I've migrated to Lua and the large amount of Neovim specific plugins (many that heavily depend on async for non-blocking operation of for instance picking or completion).
Things may have settled since then, maybe that’s why you think that this phrase looks odd.