I don't think TD throws is necessarily a good comparison of the two QBs. Far too many other factors influence that.
Didn't JG sit on the bench a lot of those years, while Goff has been a starter since about midway through his first season 3 years ago?
Looking at a stats page, if you chose to compare Steve Young's 1st full year as a starter against Goff, Goff would come out ahead. Joe Montana's first full year as a starter he threw 19 TDs, Goff threw 28. I'm not prepared to stay that Goff is better than Joe or Steve.
I'm not defending JG, we really don't know how good he could really be. Won't know anything more this year. Be charitable, give him time. Maybe he turns out to be a dud, or the next Montana.