Merging words into one. When is it allowed?

Solution 1:

The compounding is one of the ways new words are formed, nothing mystical here. If you look at various English compounds and how they are formed you will notice that these are different compared to your example.

If you compare "a lot" and "alot" you will find that this is not a matter of compounding, here the compounding of the meaning is not pronounced, but this is a change of grammar that would go against rules that govern phrases such as "a little" and "a few".

Finally, I am not sure but I think that such change does not occur also because it would change the emphasis - "alot" vs "a lot".