I agree with you. The first half can't stand alone (i.e stop and be complete with a period instead of where the semicolon is placed):
"Like all text mediums where...may have...n, n, and n." (It does that dangling thing.). Without the second half (post-semicolon) it is incorrect. And as the second half uses "those" distinctions referring to the pre-semicolon list, it likewise cannot stand alone. So, using a semicolon here is incorrect.
A Grammarianista could tell you why, but there's something about the position of "those distinctions" relative to its constituents in the syntax that forces the sentence to keep going - dependent clauses?
(I think the original author meant to use "As" or "Because" or "Since" and the choice of semicolon has an implied "therforeness" to it referring to "dictionaries..." in which case, a semicolon would still be incorrect.)
@sumelic - I don't think the semicolon can be used in this place in this list. However, there is a way that listing does use both in the same sentence. For listing with commas and semicolons, here's an example from grammar monster:
- "You should choose ham, chicken, or char-grilled vegetable sandwiches; cups of tea, Bovril, or coffee (if you don't mind them lukewarm); or red wine (one of the few options that's drinkable when lukewarm)."
@BeerBeard- Here's a semicolon culture-thing you might find interesting, if you aren't already aware of it...
"When writing, a semicolon is used when a writer could have ended the sentence, but chose to pause, and continue on."