Motor Homes for Sale can be quite a tricky subject - no pun intended. Private versus Dealer is quite the discussion.
We've all had varying opinions of many subjects. This is no exception!! I think the biggest argument in favor of your opinion is how your personal experience is/was with purchasing an RV.
We purchased ours from a private seller. The Internet provides such easy access to reviews, vehicles for sale, accident data, etc. Each day it is getting easier to either list an RV for Sale or find an RV for Sale. Motor Homes for Sale are literally all over the country.
We found the hardest part was not getting emotionally attached to a vehicle, especially when you haven't even seen it!!! We had found a really nice used RV Motor Home on eBay. We were very new at this and almost gave a huge deposit to hold it. After getting a grip, we research it more and found out if was a scam sale!!! They wanted us to send money to them, even though they didn't actually have the title in their possession. Worse, they even encouraged us to get a loan from a relative so we could send all the money as a cash sale. Each email became more of a "scam" from them. No telephone calls either - all emails. This had nothing to do with eBay! They're fine, it was just some scam sellers on it.
We would recommend trying to research first what you really want in an RV. Slides, floor-plans, brands, must haves, etc. Once you've narrowed that down, then try searching online for that type of RV you've decided upon. Again, keep your emotions intact!
When we were looking for ours, we found it in Alabama (we were in NJ). After several conversations with the owner and reviewing his info and pictures, we got on a plane and flew down to see it. This was going to be our Full time home - we had to physically see it and discuss with the owner.
We were very fortunate - nicest gentleman in the world. He had all the maintenance records, purchase info, etc. Karma was with us, we had no real idea what the heck we were buying. We just had a great feeling about the seller and the RV itself.
Turned out to be the best decision we made - an awesome Motor Home at a perfect price with all the amenities we wanted and many we didn't even know about! It even had air suspension - awesome feature to a big motor home!
Dealers are another subject in itself. Before buying from a dealer, I would very seriously check them out - Better Business Bureau, Google Maps, online reviews, etc. We've all read the horror stories of people buying a new - or used - RV with terrible Dealer issues - no walk-thru, damaged at delivery, broken and no-working items, etc. etc. As we've all met, some "Buyers" are no better to deal with either!! This can cause a 1 Star Review for an actually good dealer. Google Maps offers an excellent 5 Star Rating service for just about every business in the World - be sure to check any potential dealer thru them.
Financing issues are another item to be very careful with. We arranged our own money for the purchase. We knew exactly what the terms were and whom we were using. Again, we wanted to control the purchase ourselves. A Dealer will typically offer some type of financing that may provide them an incentive to purchase and finance thru them - not always a win-win for you.