This has pretty much been bugging me since the beginning of time, but the recent sanctions discussions really drive it home--arguing by analogy is a terrible, terrible way to get a point across. It is what people do when they (i) do not have a strong argument on the substance of the claim (ii) do not know how to articulate their point, and/or (iii) they have exhausted all standard arguments and just want to be argumentative.
The other main problem is that the vast majority of situations just aren't comparable enough to make any sort of analogy worthwhile. Even if they are, many people aren't able to make the infinite clarifications/caveats/distinctions necessary to satisfy those that will challenge the analogy. Therein lies the issue: 95% of arguments on this board (and in actual conversations, etc.) involving analogies devolve into a sub-thread debating the merits of the analogy itself rather than the substance of the discussion.
What was the point of this? I don't know. Raise awareness about a pretty minor issue? Is it still the offseason? Yeah.