Exactly, there are so many articles showing how costly context switches are, especially for software developers. By saying hi in a separate message you are for

Exactly, there are so many articles showing how costly context switches are, especially for software developers. By saying hi in a separate message you are forcing the recipient to perform a completely avoidable context switch while also priming them for another. A cordial greeting before an ask is mostly an empty gesture anyway. If you actually care how someone's day is going, ask in person or via a message with more substance.