Why do some websites not want you using a private browser?

Because private browsing can be used to circumvent the ways that they enforce paywalls (such as preventing people from reading more than a certain number of free articles per month).

If you are in anonymous, they can’t track you. And many websites make a good but of money selling your information (that you were on their site) to aggregators, who then try to do targeted advertising.

If you won’t let yourself be identified, you have no value to them.

Because they are money hungry assholes. Same reason why they won’t let you use the site if you have adblock. @elbanditoroso and @JeSuisRickSpringfield got it right.
Sites like Pandora (if you are using the free version) limit the skips you can do on a station. People found out that if you went to incognito you could either get more skips or unlimited. I don’t believe Pandora forces you to be on a regular browser, but it’s things like that that would persuade a company/site to do that.

Thanks guys. I don’t use a private browsing window very often, but I’d just been noticing blocked access to some sites lately.

The only thing a private browser does is not keep a history of your internet travels. Obviously, some websites intrude into your life to look at your browsing history. If there is not one, they can’t try to sell you the things you’ve already shopped for.

You can’t be tracked & they can’t sell your private info to the highest bidder!!! In the beginning of using ad blocker, I thought that the news sites were blocking me from seeing their site & then I discovered that IF I didn’t whitelist them that I could still get through.. I’ve also decided that any site that seriously won’t allow me in really doesn’t need my info & I go elsewhere. I don’t “need” them to complete my day as there are other sites out there giving me the same info so I dig a little further!!!

I really liked using the duckduckgo search engine so I started using the duckduckgo browser on my cell. Most sites allow me in with only a few being way too stubborn, so I refuse to allow them to see my info & I work a little harder to find what I need!!!

It restricts their information gathering.

There can be many reasons behind it. Like some websites gather your information to track you and with this they can’t track your location.