In this anwser https://japanese.stackexchange.com/a/39042/55243 it says that の after adjectives is interchangable with こと/もの. It gives an example:
の after an adjective is mainly もの, but it can be こと in some contexts:
大きいのを着た。 = 大きいものを着た。
I wore the big (bigger) one.
大きいのはいいことだ。 = 大きいことはいいことだ。
Being big is good.
But when would one use adjective+の over adjective+こと/もの and vice-versa? Like for example in
「町に人が多い のは 当然だ。車が多い のも 当然だ。」
"It is natural that there are a lot of people in the town. It is also natural that there are a lot of cars in the town." .
what happens if you replace 多いの with 多いこと?