They're objecting to the simultaneous existence of two DOM standards, to the procedure used by W3C to move forward on the W3C's standard, and to substantive issues in the W3C's fork. Each of the objections refers to the W3C's DOM spec as a "fork". The objectors are members of the WHATWG steering group. The title seems about as neutral a description as can be written.

This is a hazard of posting into message threads rather than articles and blog posts, but "all the mainstream browser vendors object to a W3C standard" seemed interesting enough an event to override that concern.