Well practically - the 'system' isn't content aware.
are SE algorithms designed to catch it?
As such, no - there's no magic algorithms that catch voting on a specific topic. That said, unless a site's super high volume like Stack Overflow (and sometimes even there - since folks often focus on a specific language or field), people are going to notice if say, all the questions on left handed carpentry are downvoted. If there's an obvious human noticeable pattern, likely someone's going to let a mod know. While we can't see voting, community managers can. If you do notice something like that flag a post, and give as much information as you can on the flag.
It's also worth consider (even if it's heavily a MSE issue) some 'valid' topics may be controversial and 'organic' downvotes tend to be valid even if there's a certain degree of 'voting against the topic, rather than the post'.
This is also occasionally true when there's no 'topical' pattern but someone's say randomly voting on stuff for a badge.
While I personally try not to stress about the odd downvote, I do feel I have noticed patterns in questions pertaining to certain topics getting downvoted.
This can be a thing, but in general if a post has value overall, a single downvote's going to get drowned out by upvotes
I can see why some people might have a financial interest in limiting the spread of certain niche information.
One person's 'niche information' can be another person's pet peeve. Or well it could be general crankery. I don't think people generally downvote out of 'financial interests'
Or it could just be that people who know about certain topics are especially irritable and impatient.
Well - a lot of technical folks... tend to be?
So practically it 'could' be a problem but unless there's organised, noticeable downvoting the effects ought to be limited