This question concerns tourists and 'visitors' only, it is not about those seeking long-term migration strategies.
The rule is Paragraph 41 concerning visitors. The clause is (ii), and in 2014 this clause was expanded to include this text...
and does not intend to live for extended periods in the United Kingdom through frequent or successive visits; and
This new text is clearly directed at something. But what? Juxtaposed to this rule, there is a Schengen rule that requires a visitor to undergo a cooling off period such that the rolling 90 days out of 180 days is not violated. Because the UK qualifies as a place where a person can spend their Schengen cooling off period and the UK is adjacent to the Schengen zone, visitors may be attracted to that strategy.
Surely the rule is worded to cover a lot of 'grey areas' that the authorities see as borderline abuse, such as digital nomads who work on foreign-based contracts, and people who are attempting to qualify for residency under Article 8, and people who might be visiting the UK a lot because they are traffickers or drug dealers. It probably also covers people who are conducting long-distance relationships because such people are not bona fide visitors along with people who frequently come and go with no apparent reason who are also not considered to be bona fide visitors.
I'm not asking if you agree with the rule, or if you think the rule will be effective; I am happy to take it as read that the rule exists and will be enforced until Parliament or the courts change it.
Would this new rule affect people who habitually use the UK as a place to reset their Schengen clock? If so, how would they be affected, and why doesn't the rule explicitly say 'Schengen' cooling off period? Is there a possibility that they would be refused entry? Or have their leave to enter shortened? How many times can a person make successive visits before this happens?