Obviously, somewhere, somehow, somebody or something at least thought about the possibility of having something with teeth strain for krill. I still don't see a possibility of that "evolving" into baleen or of an animal any larger than a seal living that way since there is a sort of a square/cube problem inherent in the process so that a larger animal would not be able to take in sufficient amounts of krill in such a manner.
Whales on the other hand had already gotten much larger before baleen whales first appeared and there is no evidence of any whale ever using teeth to strain for krill or plankton, at least to my knowledge.
Baleen of course do not look like teeth at all:
Again, predatory whales kill large fish and mammals with their teeth and eat them. A whale whose teeth started to look the least bit like baleen would be lost as to what to do next. All his instincts would be worthless.
What the evidence indicates is that the changes which produced baleen and the teeth of the crabeater seal alike were engineering changes and modifications in prehistoric times, and that whatever or whoever was making such changes has since found other avocations and is no longer doing so.