Ditto what others said for the most part - I may respond to general "buddy wanted" messages that are more of a group thing in the forum but for the most part take the conversation to private messages or e-mail.
I can personally say I have dove with 4-5 people from dive buddy in the past year at a couple of different dive sites and have had excellent experiences every time.
Also, during the busier portion of the dive season, when many of us already have a booked dive schedule it is easier to ask further in advance. If you post on Wednesday asking for a dive buddy that weekend it may be tough for people to make it. Asking for 2-4 weeks out gives people more flexibility to work their dive schedule to meet you.