To be fair, without the HL3 memes, would Valve ever become as massive as they are now without them constantly teasing and playing into it?
(answer: probably, but I would like to believe that this is one of the greatest unintended marketing tactics of the 21st century).
half life releases were tied to new platforms, such as HL2 and its physics engine, or HL Alex and VR kits.
it's like Nintendo having a Mario game for their new hardware, e.g. Mario 64, etc.
there weren't that many teases, nor is it great marketing; CS:GO competitive e-sports is better marketed and probably made Valve more money than any HL wink-wink-nudge-nudge ever would.
Valve had near-total dominance over PC gaming distribution before HL3 even became a meme.