I couldn't find clear literature supporting the claim that trimming split ends prevents them from traveling up the hair, thus increasing overall hair durability.
This 2015 article from the International Journal of Trichology says
Patients want their hair to be resistant to breakage with no split ends. Hair strength is a mix of hair body mass and resistance to breakage. A strong hair is a hair with its full capacity of growing healthy in both diameter and length and an intact cuticle and cortex. [...] But, split ends happen when the cuticle is removed (damaged) and the cortex-cortex CMC serves as a route for the propagation of axial splits in the fiber, leading to the formation of cracks and split ends.
(The cuticle is the outer layer of hair strands, which is damaged in split ends).
The abstract of a research paper published by Interface Focus says
Splitting of hair, creating ‘split ends’, is a very common problem which
has been extensively documented. However, the mechanics underlying
the splitting phenomenon are poorly understood. [...] We
tested straight strands of human hair, comparing low-quality hair (from a
subject who experienced split ends) with hair from a control (non-splitting)
subject. [...] Splitting occurred in both types of hair, but with the crucial difference that in the low-quality hair, splits originated inside the hair strand and propagated longitudinally over considerable distances, while in the control hair, splits originated at the strand surface and remained short.
While both sources refer to a propagation of the split, it's unclear to me whether that propagation only occurs up to a point not far from the tip or if it spreads further unto non-split hair.
What is clear from the sources is that cosmetic procedures and brushing your hair too forcefully definitely produce split ends:
The problem may occur naturally but is often linked to cosmetic treatments such as bleaching, straightening and blow-drying. [...] Much has been written about the effects of everyday actions (e.g. brushing, drying [24] and sunlight [26]) and cosmetic treatments (e.g. bleaching [26], curling [27] and dying [28]) as well as the effects of products intended to reduce or repair damage [29].
(From the same Interface Focus paper).
In summary, I would not believe this claim as I couldn't find any reliable source whatsoever confirming it. The burden of proof is on the claimants, of course. What does seem reasonable is that trimming them might make your hair appear healthier, since the split ends would be (temporarily) gone.
You're right to note that some of the people spreading this idea
also have a significant financial interest in suggesting frequent haircuts
Healthline.com is an unreliable source as its written by non-experts and has repeatedly posted misinformation. I don't know Self.com or Stylecraze.com, but they both seem like "beauty advice" websites with every incentive to shame or dupe consumers into buying "beauty products" and the like. I believe this sort of websites mostly just muddy the waters on factual topics like this one.
On another note, I was unpleasantly surprised by Google Scholar showing results for Discereon.com, a self-described "beauty platform" with no credentials or reputation whatsoever, mixed among the reputable scientific journals. I then wished to inform Google Scholar of this erroneous result but they have no feedback or reporting method whatsoever.
