Let me start off by saying, I don't think this is that new but it is the first time in a long time I've seen an official response by a Bing representative that they no longer support the link commands on Bing Search.
A Bing Help thread has Duane Forrester, an official Bing representative, replying to an SEO about the link command not functioning properly on Bing.
Those functions have not be accurately supported for a long time. You can see a full view of known backlink sinside your Bing Webmatser Tools account. Links, domains, URLs, anchor text, etc. all available there.
With Yahoo Site Explorer being dead it leaves SEOs with only paid tools as an option.
Forum discussion at Bing Help.