Using 'opinion-based' as a term of condemnation on this site (as on other Stack Exchange sites) was originally intended to rule out the questions like:
What is the cutest word for . . . ?
What is the most creative way of expressing . . . ?
Which way of expressing . . . do you like the best?
Such questions are indeed incompatible with the aims of the site, and deserve to be promptly closed. Some regular contributors to this site, however, seem to be using 'opinion-based' as a general term of condemnation that can be applied to any question that they disapprove of, even if it is not at all like the above examples, as long as it involves opinions in some way.
Most of the questions that involve debatable opinions can, however, be answered in a way that is not itself a matter of opinion. One can summarize the disagreements that exist on a particular matter and the state of debate on them, without that summary itself being a matter of debate. The questions that ask whether it is correct or advisable to use a certain word in a certain way, can be answered with something along the following lines:
Some people object to this use of the word; their reasons are A, B, and C. Others refute these reasons by arguing D, E, and F. Yet others accept A, B, C as having some force, but argue that they can be outweighed by G, H, and I.
Posting such an answer fits the aims of this site very well, and it is unfortunate that it sometimes gets precluded by an indiscriminate use of the 'primarily opinion-based' reason for closing.