Not surprisingly, Kofi Annan has thrown in the towel on Syria. After more than five months as the UN’s special envoy to Syria, Annan has recognised his “peace plan” is a dead letter and announced he will not seek to have his mandate renewed at the end of the month.

Annan, a former UN general secretary, is one of the world’s most experienced and respected diplomats. But some tasks are simply beyond the reach of diplomacy. Although Annan succeeded in getting both sides in the Syrian conflict to endorse his plan, getting them to actually observe it turned out to be beyond him — as it would probably have been beyond anyone.

That’s not to say nothing has changed in Syria in the meantime. The regime of Bashar al-Assad has suffered a number of setbacks, most recently the exceptional difficulty it seems to be having this week in reasserting control of Aleppo. It is now clearer than ever that Assad’s departure is the only realistic outcome. But many Syrians have died to get to this point, with no doubt many more to come.

Annan is clear about the blame for this state of affairs: “The government has attempted to suppress, through extreme violence, a popular and widespread movement that, after 40 years of dictatorship, has decided it can no longer be intimidated.” He also states bluntly, for the first time, that “Assad must leave office”.

But many commentators, including Annan himself, are also trying to maintain a veneer of even-handedness. Annan calls for “genuine compromise on all sides”, while the BBC’s Barbara Plett slides into moral equivalence: “Western states never stopped talking about the need for regime change … Russia never stopped talking about the illegitimacy of outside interference … It continued to supply weapons to the regime, while regional countries quietly armed and financed the opposition.”

Certainly there is blame to go around. The anti-Assad Sunni states do not come with clean hands (see “Bahrain” for details) and the Free Syrian Army stands accused of its own atrocities in the conflict. The otherwise deplorable polemics of the regime and its apologists do contain some truth on this score.  It’s rare for anyone to emerge from a civil war with much credit.

Nonetheless, there’s also a fundamental difference. The regime has always had it in its power to end the conflict by demonstrating a willingness to cede power and embark on genuine democratic change. The opposition has no such opportunity: the only way its leaders can bring peace is by laying down their arms and either going into exile or staying and waiting to be killed. Whatever horrors are happening on the ground, Assad has ultimate responsibility for them in a way the opposition simply does not.

The even-handedness may be just a pose. If Annan knows (as he surely does) that the only hope is for the regime and its supporters to give in, then talk about compromise and peaceful transition may help to make it more palatable. (On the other hand, emphasising the sins of the Syrian opposition seems more likely to increase Assad’s intransigence rather than the reverse.)

It does sometimes seem, however, that in our devotion to peaceful outcomes — best exemplified by such tireless laborers as Annan — we can lose sight of the fact that sometimes there is just no realistic alternative to fighting. We treasure the times when autocrats have been brought down by non-violent protest, but we forget that it doesn’t always happen that way, and that many nations have had to pay a high price in blood for their freedom.

Writing for Al-Jazeera, Larbi Sadiki laments that “the Syrian revolution may be taking a route in which the Syrians themselves have only limited control over its pace, strategies and outcomes. A revolution that started out peacefully has become one of tragedy and loss.” But he ends on a hopeful note: “It will be worth it when and if authoritarian rule is defeated.”