That isn't true.
If I had to assume, I've dealt with about 20 different anacondas to date, greens & yellows. These yellows were bred by glasscages and they honestly don't know anything IMO, because of what they said when I asked them some questions. The only yellows I've been bit by were their yearlings.
I've been struck at way more times by burmese and out of the 30 or so I've dealt with majority have tried to tag me.
Anacondas - 3/20
Burms - 22/30
I've never dealt with a WC burm eithier to top that off, and I've dealt with 2 WC anacondas, one being a green.