So… what's changing? Profiles have been there for decade(s), is it just an alternative UI for folks who were unable to run firefox -p, or is there anything more substantial?
They like to click and icon and create/switch profile. Chrome, edge and many other browsers had this feature for ever. Not having ability to easily switch profiles is only reason I did not switch to Firefox full time even though I quite like the multi containers extension in Firefox for managing bazillion AWS accounts.
You just have to add the -p in the shortcut properties.