You know, in the first couple of decades of Trek fandom, you never heard anyone use the word "canon," not that I recall. Because there was little or no new screen Trek on the horizon and thus the prospect of something in the tie-ins being contradicted was a non-issue. The risk of contradiction did exist in the era when new Trek was continuously being produced for TV, and that's when "canon" became a buzzword -- but there is
no new Prime-universe canon being produced and isn't likely to be anymore, so it is once again a non-issue. The tie-ins are the only game in town, so saying "they aren't canon" is a totally meaningless set of syllables.
Of course, tie-ins can still contradict each other; Pocket, IDW, and ST Online
all have separate and incompatible continuities, sometimes more than one per company. But that's always been the way. Again, in those early days, the tie-ins went in a lot of different directions. Since there wasn't any new "gospel" being produced, or at least very little of it, it just didn't seem that important whether a story conformed to some singular "real" version of things. It was an exercise in make-believe, something where authors and fans were free to use their imaginations to fill in the gaps, and it was much more individualized. None of this modern attitude of authoritarian canon than fans have to submit and conform to or else... something. It was a lot more populist than that.