One of the benefits to using my own domain for sale landing pages is that I can control and access the visitor logs and stats. Tracking visitors to landing page by IP address is an invaluable tool for me.
I’ll give you one example of why this data can be helpful. I am currently in a negotiation with a prospective buyer to sell a domain name. The person made an offer, and I shared the purchase price. I was told his partners think the price is too high and then radio silence. Ordinarily, I might think the deal is dead and either let it die or try to make a price concession. With my tracking stats, I can see that the prospect has visited the landing page several times. Even though there is radio silence, I know he is still interested.
I am not sure if any parking services or landing page operators allow domain registrant clients to track visitors. It can helpful to get this intel, particularly if the domain name has a BIN price listed on it. If a landing page gets lots of traffic but few inquiries or offers, perhaps that is an indicator that prospects believe the price is too high.
For me, tracking visitors can allow me to see where visitors are coming from and potentially who they are before they inquire. In addition, when I receive a phone call about a domain name, I can know in advance which name someone is calling about to be a bit more prepared if/when I answer the phone.
Tracking visitor stats, especially geolocation and IP information is helpful to me, and it is one advantage of hosting my own landing page inquiry and offer forms.