The short answer: yes
Disney pays authorized vacation planners a commission on the package you book — the resort, tickets, and any add-ons. That commission comes out of Disney's own margin, not from an extra fee tacked onto your reservation. You pay the exact same published price you'd pay booking directly with Disney.
So what's the catch?
There isn't one, and that's worth being direct about rather than hedging. A planner doesn't mark up your room rate, doesn't add a booking fee, and has no financial incentive to upsell you into a bigger package than you want — the commission structure doesn't work that way. What a planner does have an incentive to do is get the booking made and keep you happy enough to come back or refer a friend, since that's how the relationship actually pays off for them long-term.
What you're actually getting for that commission
The free part is the price. The value is everything else: someone building your itinerary around how your specific family travels, securing dining reservations the moment they open, planning ride strategy, watching for discounts after you've booked, and being available if something goes sideways mid-trip — a delayed flight, a sick kid, a resort issue.
None of that changes what you pay Disney. It changes how much of the planning burden sits on you versus on someone who does this for a living.
When it might not be the right fit
If you've already done the trip several times, know exactly what you want, and enjoy doing the research yourself, a planner may add less value for you specifically — the price is the same either way, so there's no financial downside to using one, but the time-saving benefit matters less if you don't need the time saved.