I was wondering if the editors really follow the list of reviewers the author/s suggested upon the manuscript submission in the journal?
If your paper is especially esoteric, they might. They might find it difficult to find another reviewer and so the list will help them. But they would rather send the paper to someone that they can assume will be unbiased and evaluate the paper on its own and not because of a possible relationship to the author.
But, your list is also a resource to the editor who is looking in the long term to build a large "stable" of reviewers. It may be that someone you list is not chosen for your paper but for another paper on a similar topic sometime in the future.
In addition, the list might give an editor an idea about the "sort of person" who would be a good reviewer, rather than a specific person.
Ultimately, though, the editor needs someone he/she can trust to do an impartial but thorough review.
Sometimes, and it varies by editor. On a personal level I try not to use suggested reviewers unless I've really run out of ideas (which rarely happens), because of two reasons:
- There've been studies that show that suggested reviewers are more favourable to a paper than those found by the editor.
- Peer review fraud where the authors, e.g., list themselves as the reviewer using a different name.
However there are also editors who think that it's unfair to the author if they judge the submission relying solely on editor-found reviewers, precisely because these reviewers are less favourable than author-suggested ones. This group might invite one reviewer themselves, and one author-suggested reviewer.
It's also possible that the editor is lazy/overworked/believes in the authors' integrity etc and relies entirely on suggested reviewers.