In France, and I believe in many other places as well, you can't have a noncompete without proper compensation. Compensation is relative to how it will affect the former employee career, it is usually less than a full wage, but it can be that if it makes finding a new job particularly difficult.
There have been a trend at one time of bullshit noncompete clauses that were too broad and didn't come with compensation, these are not enforceable. If they tried to sue the employee (they don't), they would be laughed off by the judge.
The norm there is paid time off between jobs (“gardening leave”). Everyone knows it is part of the system and that a mid level or senior hire can’t start right away. They also buy out still vesting bonuses and the like.
It’s quite a civilized system and I think the law ought to leave it alone, while addressing abusive ones like we have in tech.
If we assume that the financial sector is good for society, then a productive element of it is idling causing inefficiencies leading to higher fees.
If the assumption is incorrect, then the financial sector is not a productive part of the economy. In this case the worker's vacation is irrelevant since it's just a manifestation of the parasitical nature of it.
Either way normal people are paying for this civilized system's largesse.
The truth is somewhere in between. The role of the financial sector is to match capital with projects needing capital needs. Since the 80s (?) this is an insignificantly small portion of modern finance - most of it is parasitical sloshing of funds around to either gather fees or launder money.
If the answer is no, then you should reconsider thinking that garden leave is bad. It’s essentially a buffer that covers the switching cost for agents needing to decide which principal they work for.
If you removed garden leave you’d have a higher up front cost for rational actors who needed to account for the fact that they could lose their income stream at any moment if they were fired