A lot of the fanon about Shen Wei bewilders me, tbh. Though this one does have some canon basis behind it. It seems plausible enough to assume that Dixing didn't have concentrated sweets back then (they seem to lag behind Haixing, development-wise, plus normal plants don't grow underground), but Shen Wei seems to have spent a lot of time on Haixing even as a child, so he'd have encountered Haixing sweets, at least? Though what with the meteor strike, such luxuries would have been in short supply, so maybe not.

But, yeah, the point of the whole lollipop scene wasn't anything to do with the taste/novelty of candy. After all, it was a metaphor for "lightening up enough to try out new things, even if they're things you didn't think you fancied before." Since Shen Wei canonically doesn't like sweets but loved the lollipop because it was Kunlun's gift to him. (Also, there had to be some basis for the lollipop wrapper-encased pendant!)