Therein lies the main problem with this article. Not that the assumption invalidates the conclusions, it's just that, as you said, they can't be generalised.lillitheris wrote...
What-if, no moon.
This assumes the planet is Earth, of course, so it can‘t be directly generalized.
Basically all the consequences described in the article are due to one major difference - the speed of rotation. We know that the Earth rotated much faster billions of years ago and that consequently the moon used to orbit much closer. However, it is wrong to assume that this faster rate of rotation is typical of 'terrestrial' planets in other solar systems. Even in our own system Mars has similar rotational period as the Earth despite not having a moon (yes, I know about Deimos and Phobos, I'm talking about big moons like Luna; those two tiny captured asteroids have negligible effect on Mars' rotation). It is also quite possible that Earth's earlier rapid rotation may have been at least partially caused by the collision (presumably with about a Mars sized planet) that created the Moon in the first place.
Therefore, while the assumption in the article are valid within its scope (it does after all ask what would be different if the Earth had no moon), the conclusions are not really useful when thinking about other planets.
There are however other consequences of not having a moon, ones not mentioned in the article but that have been brought up in this thread. The main one is the effect of a moon on (de)stabilising the planet's axis of rotation and how that affects the evolution of life.
However, that issue is surprisingly complex and I don't think a definitive answer can really be given. While it's true that simulations of Earth have shown its axis of rotation becoming wildly unstable without the Moon, this again cannot be readily generalised to other planets. The thing is, this instability of rotation is caused by a chaotic interaction of the gravitational effects of other bodies in the solar system, which is subject to a great number of parameters - the mass and distance of the star, the masses and distances of other planets, the eccentricity and inclination of planetary orbits, the distribution of land masses and oceans on the planet in question, etc.
Consequently, the effect of not having a moon on the planet's axis of rotation can be anything from catastrophic to negligible or even beneficial.





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