It’s a good thing that attacking Libya has had that powerful deterrent effect on other authoritarian regimes that war supporters said it would have. The Post reports :
Violent protests continued to roil Syria on Sunday as human rights activists reported that President Bashar al-Assad was using soldiers and tanks for the first time against demonstrators and sealing off the port city of Baniyas.
There was never any reason  to believe that attacking Libya would discourage other authoritarian governments from using massive violence to counter protests. It was always just as likely  to teach authoritarian governments to react more quickly and with even greater violence. Be that as it may, it is important to remember that this was repeatedly cited by advocates of the Libyan war as an important reason to intervene in Libya. Evidently, someone forgot to tell Assad that the Libyan war was meant as a message for him. According to Marc Lynch , discouraging other regime crackdowns was “one of the strongest reasons” to intervene. Shadi Hamid argued  something similar:
By contrast, if Libya fails, Qaddafi stays in power, and the rebels are crushed, it will mark the end of what’s left of the Arab spring. It will send a dangerous message to autocrats: if you want to stay in power, do what Qaddafi did.change_me
Of course, authoritarian rulers already knew that this is what might be required to stay in power, and they haven’t been waiting on a conclusion to the Libyan crisis to reach this conclusion. What is remarkable is how quickly and thoroughly the pro-democracy argument for the Libyan war has been discredited by events. The forced pro-democracy argument for attacking Libya has been repudiated in a matter of weeks as it was bound to be, because it was a strained effort to cloak an ill-advised military intervention in democratic rhetoric.
At the risk of repeating myself, I want to point out that the “where we can, we must” argument for humanitarian intervention directly contradicts and undermines all of the arguments claiming that attacking Libya will set a precedent, enforce a norm, or create a deterrent against similar regime violence elsewhere. If we believe the “where we can, we must” argument, it doesn’t matter that circumstances make intervention in other crises impractical or impossible, because that isn’t an argument against intervening where it is possible. However, the precedent-setting or deterrent-creating argument holds up only if Libya is not a special case. For authoritarian regimes to take seriously a threat of outside intervention that would discourage them from cracking down violently on protests, there has to be the possibility that the Libyan intervention can be repeated. As many of the supporters of the Libyan war already acknowledge, and according to the standard Obama laid out in his March 28 speech, the conditions that made the attack on Libya possible are unlikely to occur again.
That doesn’t mean that Libya isn’t going to create unrealistic expectations among protest movements. Giving weak opposition movements  an incentive to pick fights with their governments they cannot hope to win on their own is an effect that the Libyan war very well might have. Since there is little chance that the coalition that organized intervention in Libya will come together again in other situations, that creates the potential for giving opposition movements false hope and makes the resort to ineffective armed rebellion appear like a short-cut to achieving political goals. That gives peaceful political protest the appearance of a foolish, hopeless way to oppose a regime, and makes armed resistance seem much more effective, which is pretty much the opposite of what all of the sympathizers of the “Arab Spring” say that they want.