If you'd like to thank someone, why don't you?
Um, I just did.
In "I would like to thank...," "would like to" means "I'm doing it even as I speak." But you won't find that meaning of in dictionaries -- at least, not anywhere you can find it, in any recognizable form. I believe this is called an "implicit performative utterance" -- "performative" because the statement actually does what it refers to, and "implicit" because it doesn't do it literally and directly, the way, for instance, "I hereby thank ..." would.
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