I've been using Unix for 20 years, switch to pwsh 2 years ago, never typed backslash ever.
In other words, you can balance your environment for speed vs features.
I believe Pwsh will get considerably faster in the future given that optimizing it will pay out on nano server which currently boots faster then PowerShell is loaded in it afterwards (which rly sux).
bash requires scraping everything and is inherently brittle as a result, which has always bothered me much more.
This was a late-breaking change and for a few versions of DOS you could set SWITCHAR=- in CONFIG.SYS to get the Unix behavior. When set "dir /s C:\whatever" becomes "dir -s c:/whatever".
You can literally blame IBM for this divergence. Without them pitching a fit about it DOS/Windows would have had the same switch syntax and path separators as Unix.