What kind of people do you want to attract? Do you think the best writers are attracted by the best parties?
Wikipedia has loads of contributors in Germany. That is because of a long history of German intellectualism, it is not because Wikimedia is throwing parties. If Wikimedia were as global as you suggest, where are the parties in Iran and Russia? Are these parties without alcohol? I hope so, because we wouldn't want to exclude the muslim world, right?
I say this as a Wikipedia contributor since 2005 with 16k edits.
What? They aren't a fraternity, so I don't think drinking is mandatory.
If you look at any large organization it has these kinds of frivolous events. Among other things, they let the leadership get a sense of the social environment and how it reacts to some of their ideas with less filtering. I personally don't attend most of these events, but it is really a silly direction to assume everything that is not technically necessary is a waste of money.
If you have a new point to make, it's best to make it as a top level comment rather than trying to prop yourself up as opposing a point someone never made.
Though tbh "other orgs do it" is never a good argument, but it is especially bad here.
WMF's per-employee T&E cost is apparently $7k/year. Working in sales at a company you've heard of, I've flown single flights and attended single dinners that cost more than that.
They're an online wikipedia. Their costs keep ballooning, and not to pay for things that I care about when I donate money to support their core mission.
Regardless, do you really begrudge the CEO visiting these places?
I get where you're coming from: it's easy to roll your eyes and dismiss this kind of thing as political correctness, pointless "diversity and inclusion" work, pandering to liberal friends etc.
But step back: Wikipedia aims to be the world's encyclopedia. I'm as much in awe as anyone of what a fairly narrow group of pretty obsessive contributors has been able to achieve (I just checked: I've made five tiny edits in 15 years, so not me). But Wikipedia will never succeed in its aim unless it has active contributors in places like Accra, Berlin and Chandigarh.
I honestly don't remember what the donation banners have said in past years. Did they imply they were funding servers and bandwidth only? Maybe they did. But if you actually believe in the mission of Wikipedia, you have to consider that servers and bandwidth will not be enough and that community—maybe including the odd party—is a core part of it.
In that respect, I'm not sure it's too helpful to lump it with Mozilla.