Yeah, I don't get that, because it seems to me that the friends you make along the way are mathematically indistinguishable from particles being real and having properties. It's a distinction without a difference.
Or at least, I'm interpreting "the friends you make along the way" as the sum total of the effects of a particle on the surrounding world. Saying "the particle doesn't exist, but it has effects X, Y, and Z" is the same as "the particle exists and has effects X, Y, and Z". If a distinction is not observable, then it's meaningless to quibble over whether it's "real" or not.
(Which all just proves that my interpretation isn't the one you were using....)