phrases - "more of a"or "too much of a" in a plural sense

Using "more of a" and "too much of a" is quite common, but when it comes to pluralizing these expressions, things become more complicated. I've never seen someone use these with a plural subject – I just see people rephrasing:

"He is too much of an idiot to understand."

"They are too stupid to understand."

Something I have always wondered about is whether you can pluralize those two expressions, something like "They are too much of ... ". But I cannot think of any way it would be used in the plural.

Answer

I believe there are two things at play here. One is the fact that "too much of an" is dependent on a singular-typed characteristic, so it sounds clunky when converted directly to plural. The other is whether the phrase type is an established convention or not.

Consider these examples:

He is too much of an idiot to understand.
They are too much of idiots to understand.

While the above transmutation looks like it would fit, the problem is that the construction sounds unnatural, however could work.

The next revision suffers from something of the same:

He is too much of an idiot to understand.
They are too much of an idiot to understand.

This suffers from a singular-plural disagreement and sounds unnatural to the ear. Part of the issue is that "an idiot" applies to one person.

To resolve these two issues, some changes need to be made. In order to maintain continuity, these kinds of changes can be introduced, to allow singular-singular agreement.

He is too much of an idiot to understand.
They are (all) too much of an idiot to understand. (revision 1)
They (each) are too much of an idiot to understand. (revision 2)

Wherever the singular and the plural can both receive a singular-typed adjective, the construction tends to stay the same:

He is too much of an inconvenience for us at the moment.
They are too much of an inconvenience for us at the moment.
He is too much of a liability to the company now.
They are too much of a liability to the company now.

The most important reason why this works is because the singular-typed adjective here tends to be an abstract idea rather than a word that describes an individual that is countable.