This is a questionable take on two levels.
First, yes, yes there is something magic about SF's geography, it's the closest major city to the largest VC hub in the world. These companies thrive on young talent that prefers to live in a city. It's not dissimilar to the gold rush 170 years ago when you think about it.
Second, what do you mean "San Francisco is just not suitable any more"? The tech companies and their employees are the least impacted by rising housing costs. By and large they are doing alright, so what is their incentive to uproot everything and randomly go roll the dice somewhere else which would A) not have a critical mass of VC in their backyard and B) will offer no guarantee of not reacting exactly the same as SF.
Keep in mind, 20 years ago there was barely any tech in San Francisco proper. Sure there tech employees who chose to live there and suffer the commute to the peninsula, as is their prerogative being free individuals residing in the US. The reason tech moved in was because SF offered tax breaks—they wanted their piece of the tax revenue and daily spending from well-to-do tech workers. If the city really felt tech being there was the problem they have a lot of levers (eg. raise taxes, zoning changes, etc) to push it out. Of course they don't want to do that because it would cause far more economic harm than good. NIMBYs are of course willing to entertain the charade of successful tech companies as the scapegoat because it keeps their home values sky high while deflecting to the amorphous "tech companies", who in fact they have zero control over policy and at best marginal interest in addressing the issue at all.