IMO, the biggest mistake the 49ers made wasn't which QB they took, but rather it was not recognizing their championship window. Imagine if they had drafted Ja'Marr Chase last year instead of any of the QBs and rolled with Jimmy G (which they did anyways). That would have been enough to put them over the top and win it all last year (IMO). They had a win-now roster needing just one more piece to get them there. But they took a long-term developmental prospect that made almost no contribution last year and left them coming up just short.
Now in year 2 Lance's rookie deal, instead of loading up to win this year while their QB is on his rookie deal, they are devoting that potential extra cap space to the bridge QB while the developmental prospect continues to develop. And by the time that prospect is really ready to contribute, all their star players who on their own rookie deals (Bosa and Deebo, among others) will be coming up for mega contract extensions and they will never really get to exploit that window of opportunity that they had this year and last.