Let us take, for example:
I wandered lonely as a cloud
That floats on high o'er vales and hills,
When all at once I saw a crowd,
A host, of golden daffodils...
This poem immediately demands the reader think about specifics - specifically specific ways of doing things, and daffodils.
What are the problems with that?
Firstly, it prevents the reader exploring their own ideas of how, for example, to wander in a lonely manner, or what they might see when doing so.
If one instead said:
I wandered lonely as a wandering lonely thing
and:
A host of things you could see a host of
then the reader's imagination is allowed to run free inserting his or her own images as applicable to their own experience.
Even better:
I did something in the way I like doing it
and:
I could see what I wanted.
thus not restricting them to wandering, being lonely, or seeing too many things at once.
Secondly, the nature question. These nature specifics - and they appear in an awful lot of poems - also exclude those readers who do not have access to 'nature'.
The city dweller is lucky if they've ever seen a vale or hill, and their knowledge of daffodils is likely to be either of that circle of yellow planted by the council on the concrete roundabout where the turn-off for Tesco is, or the drooping yellow things they've taken out of the green bucket outside the petrol station as a last minute present for Aunty Nora. These daffs are not dancing in the breeze - they're gasping for air.
So what is this poem supposed to mean to these people?
To sum up: such specifics limit the imagination of the reader and are also exclusive.
While I'm at it, may I suggest that poets are a bit too obsessed with loneliness, solitude, lying on couches, and being vacant and pensive. They should get out there, get some mates, and get a life. And if they can't be bothered to get off the couch (ok, fair enough), at least watch something decent on Netflix.