“Magic links” can end up in Bing search results, rendering them useless
Microsoft does this because they're security scanning / checking all links in every Outlook email for known phishing and malware attacks. If Bing has not seen the web page  before and it's not in the Bing dangerous web page index it first needs to check it to make a determination of if it's a phishing/malware page by scanning/indexing  it before returning that outcome back to Outlook to flag the email as dangerous.