The good reason is that all politics is corrupt, and that thinking about politics is a deceptive distraction from what Christians ought to be doing.
This is a perfectly reasonable and sensible motivation - although the consequences are pretty extreme - and include striving for silence and zero opinion on socio-political matters.
It would mean genuinely-ignoring the mainstream official and media information and interpretations on life; and there are not many people I know of who actually do that (instead, they either accept or reject - but don't ignore).
The bad reason for 'ignoring' politics is when Christians fail one or more of the 2020-21 Litmus Tests, and want to create wriggle-room by which they can continue to support Leftist causes.
This is bad, because it is dishonest. Such a person is actually just pretending to ignore politics, covertly; so that they can continue to support the globally-dominant, institutionally-pervasive side of Leftism in the spiritual war - in one or more favoured respects.
(And as of 2021; Leftism is, in actuality, on the side of purposive evil - Leftism, of course, includes All of the mainstream political parties and groups. And there is No 'political Right' in the West - only Christians (and the majority of self-identified "Christians" are fake - being covert Leftists). The non-Christian or atheist "Right" are merely a species of Leftism - as is becoming ever clearer with each passing week; as they sell-out and take-the-ticket, en masse.)
The covert-Leftism motivation is bad for at least three reasons: because it is a failure or refusal to make necessary discernments; because it is dishonestly putting socio-politics above Christianity - while pretending to do the opposite; and simply because Leftism (in its many, and mutating, manifestations) is the primary strategy of Satan.
Note added: Deciding whether someone is motivated by a genuine desire to ignore politics in order to concentrate on Christianity; or is covertly Leftist and is pretending to ignore politics in order to follow the mainstream in some (anti-Christian) respect - is, of course, a matter of judgment. And judgment is based on inference about another person's state of mind, and therefore may be wrong. Yet, judging others is both inevitable and necessary for Christians; and we must act upon our judgments. (No need, then, for Christians to feel guilty or to be evasive about judgment!) Also, we must discern and judge so often in modern life that we cannot afford to be hesitant, conflicted or squeamish about the matter; but on the contrary should strive to be swift, light-hearted and decisive in our judging of others. However, we must also be open to the possibility of our own error, and prepared to repent and revise our judgments in light of further experience.