Since when is hybridization not based on sequence?

Yet another trivial objection to an interesting study:

"A non-sequence-based method for studying copy number variation that avoids this limitation of draft sequencing is array-based comparative genomic hybridization".

I thought hybridization is indeed based on sequence. Perhaps the authors meant that the method does not require knowledge of the sequence.

Gene copy number variation spanning 60 million years of human and primate evolution.
Dumas et al. Genome Research, September 2007.