who places so much emphasis
on a particular issue
that where a candidate
stands on that issue becomes the deciding factor
in who they vote
This approach to voting can and often does result in a decrease in the voter's satisfaction with the system.
This is at least partially because their candidate or party probably votes against their wishes on many issues whereas their candidate or party typically votes for the single-issue very infrequently.
In the long term, this dissatisfaction can have a corrosive effect on the system as a whole.