Umm… Because the versions aren’t even close to being compatible? There are over 1000 code commits between version .7.1 and the upcoming version .8 alone, each one of which has the potential to break things. Not to mention we’ve added in mac compatibility and SDL compatibility (both things which the tiles need to be compatible with).
Also note that until .8 is officially released the experimental will still be listed as .7.1, despite the fact that it will be something like 95% the same as version .8.
Also ignore DownUnder, it’s just LazyCat again (and what he’s saying isn’t even true anymore).