zzzz, You will have to take my word for it that, in the case I am thinking of, we really were in a GP's surgery vs specialist hospital department scenario.
That's also why the 'just give mainstream school the same money as a Special School would receive' doesn't work in some cases:
'Oh, your patient has a brain tumour. As hospitals are really expensive, and some aren't very good with some diseases, we won't send your patient to the well-regarded specialist brain tunour surgeon in X hospital, we'll just give you the money instead, so you can do it yourself'
'But I don't have a suitable operating theatre, anaesthetist, surgery equipment, medical consultant or after care facilities'
'Oh, that's OK. Use the money we're giving you - I'm sure you can rig up something in one of your consulting rooms and retrain a few of your other staff. Everyone has the legal and ethical right right to be treated by their GP, and to be part of the GP community. No reason to send someone away to a more distant specialist.'
We'd never say that in medicine - so why do we say it about education of those with very very complex educational needs?
Could you give examples of what you would regard as 'significantly impacting' the education of others, by the way?