We’ve done a lot of framing with glazing, and even with matt papers and no space we have seen occasional problems ... albeit far fewer than with RC based papers. Epson Luster has more texture than most matt papers and as long as it is outgassed adequately will tend to stick less than gloss papers but regardless of any measures, if there is no space eventually you may have a problem. I also think with inkjet prints some of the outgassing can be exaggerated by direct contact with the glass. I’m not sure “breathing” is the best word to describe it, as there is no circulation of air in that space, but the space does impede the process.
Chemical photographs should never touch the glass, because they have a high likelihood of sticking over time due to their construction and their ability to “absorb” humidity.
My personal opinion after seeing hundreds of pieces framed and presented in a variety of ways is the space serves a little different purpose, especially if it is a little larger space such as behind a double matt, and that is to separate the print from the glass. The texture of the paper even though it is only a short distance behind the surface of the glass seems to be part of the image and separate from the high gloss of the glass, and the reflections on the glass seem detached from the image. We have framed many images where the glazing was placed in front of a liner of some type, thus creating a ½” space or so, and to me separates and identifies the glazing as intended to protect the fragile and valuable item under it.