I'll be better prepared to answer your question maybe during but most definitely after my 2025 hunts.
For now I can say, obviously not all foreign (outside the US) outfitters have a representative in the US. Personally and from my Zimbabwe experience; I have become more apprehensive on sending money, especially the amount of money for an African safari, by wire transfer to a bank account outside the US.
For those that do wire transfers routinely and are confident in sending wire transfers it probably isn't a big deal. For the first timer it most likely is concerning.
Using a booking agent gives me a bit more relief-security becuase when I deal with a booking agent here in the states, that I can simply call, give credit card information to them (especially giving out my cc info) and later as questions and /or should changes or problems need to be addressed, a simple phone call can usually takes care of it. Unlike trying to communicate with an outfitter thousands of miles away in a different time zone, in an area that doesn't have reliable phone and internet service, and the outfitter is the owner/operator/PH (and especially when) they are with client(s) on the ground.
Having the right booking agent, especially for first timers going abroad, can help relieve the stress on booking dates, (if they are coordinated with a travel agency flights, providing customs,TSA, traveling with firearms, travel/trip insurance advice and other information), and information on other than hunting activities in the area.
Is using a booking agent a necessity? No. But they can be a good asset to use.