Like any other kind of tool, there are different variations for different situations and different jobs. The reason there are so many different guns is for the same reason that there are so many different ways to turn a nut or bolt. To say a socket set is always best, and a set of wrenches is too limited to consider, would be a silly thing to say for anyone who had any experience.
Most of the time a socket set is faster, more convenient, and sometimes more versatile, while wrenches are less prone to failures, but are limited, and still can’t do everything. However wrenches afford me certain options and abilities not possible with a socket set. It is the same argument with guns.
A semi-automatic is most often the gun of choice for me, unless I expect, or anticipate a significant chance of needing, the revolver attributes I can’t so easily access with a semi-automatic, ( if at all ).
One example was carry in the mountains that I once lived in where self-defense was not limited to two legged creatures. Bears were frequent visitors to our property, often encountered upon returning home. A .357 magnum, loaded with most, or all the chambers containing a good self-defense +P .38 special, gave me a good, controllable, accurate self defense round that was not overpowered for inside the home or inside the neighborhood. Yet I could have a couple of rounds in the gun, or a speed loader on stand-by, with full house deep penetration magnums. ( this is just an example for illustration purposes ).
Occasionally I find the simplicity, and unique options offered by a revolver, to be desirable for various reasons.
Choose the tool that fits your needs, fits the job, and matches your skill level and training opportunities.
Though I was an experienced shooter, my first carry gun was a revolver. When I moved on from that, I consciously chose to keep the revolver because it had attributes I wanted to be able to return too when the situation called for it.
Semi-autos have become so good that they usually seem to be the better option for a variety of reasons but there do remain a few things that a revolver can do that an auto cannot. It just depends on what you most want or need. A good instructor can help you sort those factors out for your particular situation.