We get some anecdata about one person who didn't want a pizza party and would have preferred cash or coupons.
The rest of it is just some waffle about what some HR people think, and some wild speculation that it's because senior people get an ego boost from it.
Not worth your time.
Why do you presume employees like pizza parties?
What leads you to believe that HR-imposed mandatory, non-paid gatherings after hours are something enjoyed by employees?
Those who already want to gather after hours to socialize are already doing it, without needing HR to be involved.
I repeat: what leads you to presume this is something employees enjoy? I mean, is it conceivable to you that any random person prefers to be forced by HR to attend an event on their own personal time instead of spending it with their loved ones, or even doing something they love?
Just pointing out that for those people who are passionate about pizza parties and whether employees like them or not, the article is not helpful.