I disagree, a vacuum gauge is a valuable tool when fine tuning an engine.
You need to know how to read it and what it's telling you.
I learned how to tune with a vacuum gauge at a young age in 1979. I was taught by my dad. also learned how to get initial timing with points using a volt meter or lamp.
A vacuum gauge is right beside a wideband in the cockpit. lol
If you only knew what I know. jk