For example, I did a split about twelve days ago, and the new hive started making queens. Now this was a very aggressive hive, so we wanted to re-queen it, so about eight days in we went back and destroyed every emergency queen cell, then two days later we went back and gave them a new queen that we purchased -- one bred specifically for mite resistance and which is not africanized. If we hadn't done this then that hive would be about to get a new queen naturally (and that queen would then kill all the other about-to-hatch queens).
Though, even if they make a new queen, there will be a brood break. A brood break is a time period during which no new eggs are laid. Here it would be about three weeks, and maybe a few more days. It takes time for the new queen to hatch, get mated, and start laying. If this happens at the height of a honey flow then the hive will be made much weaker because the workers live just six weeks in that time of the year. Beekeepers tend to force a short brood break in the fall to forestall the mites, but this is a bit much.
I don't have enough experience to say for sure, but I would expect that stealing queens will typically cause loss of maybe 50% of hives -- more or less depending on the time of the year. Also, if the beekeeper inspects hives weekly (a big if, especially if the beek has thousands of hives) they will notice that the hive is queenless and will probably re-queen it sooner than the time it takes the hive to make a new queen, thus reducing the loss rate. Commercial queens are about $45, but they're not available year-round. A commercial beekeeper might even raise their own queens for themselves, so they might have better availability. So hive loss rate might be lower, though still, it's not cheap, and it's labor intensive to inspect every hive weekly.
Beekeepers who produce queens for sale breed them for various attributes, such as mite resistance, gentleness, and productivity (of honey). The queens that they use for the first stage (for making the eggs that will be grafted) are quite valuable. Though it's still not worth stealing unless you can set up a similar operation, which means there wouldn't be very many suspects.
(There are also beekeepers who artificially mate queens to better control for male genetics. That is a very labor-intensive process, and those queens are correspondingly more expensive, but the main queens probably aren't any more valuable than in the process I described above.)