According to grammar books, at all means 'in any way' and is NOT used in affirmative sentences. But in the example
It is essential to democracy that any group of citizens whose interests or desires separate them at all widely from the rest of the community should be free to decide their internal affairs for themselves,
which is from "Political Ideals" (1917) by Bertrand Russell, it is used in an affirmative sentence.
What does at all mean here? And is this usage considered to be acceptable today?