Opposition boycotts of allegedly rigged elections: anyone else see this as a cop out?

I can think of two recent cases in which the opposition to a government or referendum proposal asked their supporters to boycott, IE either not vote at all or spoil their ballots, a vote which was taking place. One was in the case of the Catalonia independence referendum in Spain last year, and one was just today, where the opposition in Russia called for people to boycott the election and the incumbent government as well as various businesses actually offered incentives to people to get out and vote, so that they could have enough voters for the election to be considered statistically valid - a sort of informal "national quorum", if you will.

There are two other recent cases which may have involved boycotts in this manner, but as I can't remember for sure and am too post-Paddy's Day hazed to go Googling it I didn't include them as examples - I believe one or more of the post-Arab Spring Egyptian elections was boycotted, and I also believe that the referendum held in Crimea a few years ago over membership of Ukraine was also boycotted by one side or the other.

It strikes me that this tactic is almost always employed by a side which, according to pre-election polls, is very likely to lose the election or referendum being held. And I have to say I find it an incredibly cynical, underhanded and cop-out tactic. If you believe that an election is subject to irregularities or ballot stuffing, protest that after the vote, no question - but it strikes me, and this is where I'm wondering if anyone agrees, that boycotting an election you're seen as likely to lose is basically a cheap way of discrediting the result. In other words, if you tell your supporters to stay home, then when you lose the election it gives you an excuse to make claims along the lines of "oh, well we boycotted it, so the results aren't a true reflection of the national mood and therefore don't "count" for anything. We might have won if we hadn't deliberately told our people not to vote, so the whole election is invalid".

We saw this with Catalonia and we're seeing it again today in Russia, where the opposition are already stating that because their supporters were asked to boycott, it means that the result itself is invalid even if no irregularities or corruption is discovered. A closely related claim is that the election is invalid because there's no "credible opposition" - which translates in my own head as "the results are invalid because nobody is popular enough to defeat the guy we don't like".

Does anyone else feel this way? I'm all for protesting and agitating over rigged and compromised elections, hell I've even supported violent rebellions against this in some extreme cases in the past. But telling people not to vote and then saying "not enough people voted so the results don't count" seems to me to be an extremely obvious, cheap, and underhanded way of trying to discredit an election which you know you're probably going to lose. Basically, it seems like these groups are trying to back the likely winner into a corner where it's like "even if you win, you didn't actually win.

If you take today's election in Russia, what exactly would it take for the opposition to be satisfied? Reading some of the arguments they're using, it seems as if they will ONLY see the election as valid if Putin doesn't win, because they believe that a majority of the people don't support him. But this is akin to the infamous Witch Trial method of drowning people to prove they aren't witches - damned if he does, damned if he doesn't. They're literally saying, if you strip back all the dressing-up of the various arguments, "if he wins, then it means the vote doesn't count". Which boils down to "the election is only valid if I get the result I want, otherwise it's bullsh!t". This is exactly what happened in Catalonia - the independence side won the referendum but the unity side said "well our people stayed home at our request so the result is meaningless". Very convenient way of preventing your side from losing an election!

This, at least to me, is a very obviously undemocratic way of thinking, and I for one find it pretty abhorrent. What do ye think?