Goff was a struggling QB under McVay, to the point where he completely lost his HC's trust. Stafford walked in and won a Super Bowl, so yeah, that trade did work out for LA. You can't just brush that aside. Goff walked into a situation where his new HC and GM had confidence in him, and built a team to accentuate his strengths. Bottom line, I don't think Goff would've won a Super Bowl with a McVay-led Rams, but I think he absolutely could in Detroit.
This trade worked out for both teams in a way that will forever be the gold standard example of Trades That Worked Out For Both Teams