It pre-dates Go by a bit for sure, and Go was already underway at Google with Rob Pike before Russ came over (per my recollection).
That said, I too use plan9port, on my mac, for Acme mainly.
Russ just fixed up the thread library so it works more uniformly (and correctly) on all platforms - including Apple Silicon.
p9p acme does introduce multi-line tag displays, though, which is hugely convenient when I want to keep track of lots of line numbers or hold a bunch of Edit commands.
For one thing it's extremely mouse-driven, which is already disqualifying in my book but to each their own.
The whole "anything can be a tag and you can execute it by clicking the middle mouse button" can seem novel and exciting if you've never used Emacs, which did the whole "everything is configurable and scriptable" a long time ago and IMO better.
Then the lack of syntax highlighting is pure elitism in my book. I tried to give that a chance but when you listen to the arguments of its proponents it often boils down to "colors are childish" and "books are black on white and we read those just fine" which makes complete sense unless you think about it for two seconds.
I genuinely don't get it. When I first read a Vi(m) tutorial it seemed esoteric, complicated and weird, but I understood why some people found it more efficient that way. Watching somebody explain acme reminds me of TempleOS, filled with weird idiosyncrasies of dubious usefulness while lacking super basic features.
Now I wanna see a B&W syntax highlighting setup that uses all the tools available to a book. Font sizes, bold/italics, the use of display fonts here and there, including Comic Sans to highlight Really Bad Ideas...
That might be true.
When you get past the snark, there is a strong argument against syntax highlighting in Plan 9. If your desk is too messy to find anything, tidy it up; if your code is too messy to read, ditto. Syntax highlighting, from this perspective, is like bringing in a mechanical excavator when the answer is to stop digging. If you look at the Plan 9 code, they practiced what they preached.
But that perspective is an elite one, that of research programmers at Bell Labs, where the code is the product.
Basically my opinion regarding using UNIX CLI + vim and emacs.
Simple anecdote: many terminal emulators highlight what they recognize as an URL, then make them clickable. Acme allows to make any text clickable and set the selection to a plumber, for action. A path, a git hash, a time stamp, whatever. This is so much better. Some terminal enulators can be used like that, foot natively on wayland, st with patches and urxvt with Perl extensions.
I dropped syntax highlighting a few years ago. My thoughts on it are not "colors are childish" and "books are black on white and we read those just fine." I don't like the computer trying to convey what is important in my text files to me via color. What I think is important and what the computer thinks is important is often different. Then why don't I configure my syntax highlighter to agree with me? It's just another configuration file to keep in sync on the computers I use, and :syntax off is right there... It's the nuclear option for being annoyed that comments are shown in light gray.
Now sam…that’s an editor I just can’t figure out how to be productive in.
If I had a need for it, or could justify the cash, I'd get one just to play around!
In the end, the workstation was so completely fused to the printer I'd end with a car-sized workstation.
Iirc Russ Cox ported Plan9 userspace to Linux when he moved to google, somehow out of frustration. Thanks for that, using acme on Unix is like a hot summer late afternoon fresh beer. Or whatever fresh beverage of your fancy.