is "groupset" an outdated concept that only mfgs are pushing?

except for shifters and possibly matching derailleurs I have mixed tons of stuff across brands and speeds and they all work fine. The front derailleur can be swapped across brands and even between speeds and they work fine. Same for most Shimano rear derailleurs. As a last resort, I put on a 7 or 8 speed thumb friction shifter and it shifts everything from 8 to 12 speeds in the rear.