Can "比" go without a subject?
[比 (object)，还要 (adjective)] = [ more (adjective), compare to (object)]


比[那刘姥姥进了大观园]，还要[土里土气]
那刘姥姥进了大观园 is  the object phrase
土里土气 is the adjective phrase


The subject is omitted in this sentence, but it is there. 

You have to have a subject to compare to an object: "Subject' (omitted) 比 [那刘姥姥进了大观园]，还要 [土里土气]"

The subject can be a noun, or another phrase