This is plain wrong. No-one manipulating the DOM is because of read-only restrictions. They're modifying the interface.

Read-only is a choice, and it's one G+ is willing to stick to (look back at Vic Gundorota's posts about "curation").

I think they're holding back a write api so that g+ doesn't become like buzz; a dumping place to pipe your other streams to. Makes sense while they establish their own user base.