Is 'flooding' allowed?
I vote for NO, let's not allow this.
At what point does answering become 'flooding'?
When two answers (of the same user) don't conflict.
That is, two answers conflict when it would be unreasonable to upvote both at the same time.
Only then, it makes sense to split.
Otherwise, it's flooding.
How should we deal with 'flooding'?
Flag for moderator attention, with a comment "flooding",
and mods can manually merge the answers.
If the answers don't contradict each other,
then it would be easier to read them in one post,
with good headings, and hopefully ordered by some logic.
It's harder to read when fragmented, displayed in random order,
and interleaved with answers by other users.
From my personal experience the majority of people refuse reading long, not very good structured texts. This is the first reason for splitting long answer into a few shorter.
I agree that the majority of people do not like reading long texts.
The users of this site are not like that,
they are not representative of the general population.
The second motivation for shorter answers is to provide information not only to OP but also to other people reading individual answers. There may be a problem quickly scan a long one for yet not known things for me whereas in answers addressing only one issue is easier distinguish if I will skip it or read it carefully.
I think it's easier to scan texts author by author.
Every author has a different mindset and writing style.
When there are multiple answers by multiple users,
the switch between styles can be a real mental burden.
Another important point is the ordering.
For example, I often address very different facets of the posted code,
such as algorithm, design, usability, best practices.
The order in which I write these sections is never random.
Sometimes I order things from most important to less important.
Other times, for beginners,
I go from easy to complex.
Sometimes I also cross-reference by section names.
The ordering and structure is very important for me.
And if I split my answers, I would lose control over that.
The fourth reason (and there exist even more ones) is than every answer has a "share" link - and I prefer to share the explanation of only one particular thing of my interest, not lost in huge bunch of other information.
That may be convenient for you,
but not for the vast majority of users of this site.
And I think that they should be your main target audience.
The reason for a nice formatting answer is to make it attractive and readable - like for the reviewed code itself.
As I explained earlier,
a split answer is not more attractive and not more readable.
I think it's the opposite.
And as far as formatting nicely,
it works precisely the same way,
whether you split answers or not.
But the main, the most important thing is that the goal of answers should be to help other, less experienced people. Not to express myself, not to save space, not to show more experienced people as I'm good, not to correct every one thing. And it is not possible without adapting to OP (estimated) level.
And if that is your true goal, I suggest to follow my counter-points and recommendations above.