I have a blog where I (used to) review SFF. Haven't posted anything for over a year, but I still get review requests. As far as I can tell all of them are for self-published books. I don't actually have a page on review guidelines (, but will put one up when I start reviewing again,) however, there is absolutely nothing suggesting I actually review self-published books on my site. There is a review index, so it's not hard to check for those that are interested.
The reality is that anyone with a review blog will receive plenty of review requests, usually from self-published authors. But reviewers will also have access to NetGalley and Edelweiss, and in many cases be able to get books directly from publishers.
Most reviewers also have a reading backlog that made me start using the phrase TBR-Mountain instead of TBR-Pile, it quickly caught on among my reviewing friends.
So basically, a self-published author a reviewer hasn't interacted with previously sending them an e-mail is just not likely to get a response. Part of the reason is that some reviewers who have responded have gotten some pretty vile responses back.*
It may not be fair to ban everyone for the actions of some people in a group, but when you have limited time for your hobby, (I don't know of anyone who makes a livving from reviewing books,) it's just a risk most don't have the energy to take.
I suggest you look closely at review sites/blogs before sending a review request. Look for those that have review guidelines that states they do accept self-published books. Read enough reviews from the reviewer/site you are sending a request to that you have an idea of their style, and write a personalised letter.
DO NOT UNDER ANY CIRCUMSTANCES send a review request with a link to buy your book on Amazon. -And yeah, I have gotten a couple of those requests...
I know this is peobably not very helpful, but it is how things are. Largely there is a seperation between those that review self-published books and those who review trade published books. Getting a review from the latter will be hard for a self-published author who doesn't socialise online with them.
* I know reviewers who have gotten threats for politely saying they do not accept review requests at all. And saying you don't accept self-published books can lead to being accused of being paid off by publishers, and hating authors. A reviewer friend who wanted to open up for self-published books gave up because of some of the responses he got.