It's true, of course, that the "chronological timeline" is an obvious and straightforward default, but I think you are being unfair to the position you are critiquing.
Many (90%+ I would say but the exact proportion doesn't matter for this) people do not have the time to process every social media post from every person they are connected to. They are only going to see N "posts" (videos, texts, questions, etc) per time unit (day / week / bathroom break). It is 100% genuinely and obviously worse to, if someone only sees...3 posts on your social network for those posts to be [someone complaining about commute, breakfast photo, angry election post] as opposed to [wedding announcement, request for a resource the user has, a close friend sharing something exciting that the user hasn't seen]. Telling users that you are showing them less interesting stuff because "they happened in chronological order" is a bad answer.
Of course social media companies do a bad job at this! They push high-conflict high-engagement content into our feeds because it makes them more money. But I think the problem of "there is a lot going on and you would like a machine to help you prioritize how to process things" is genuinely one of the pressing problems of our age and I get so frustrated when people downplay it. There is more stuff happening in my social world than I have time to fully process - that's just true. I am not interesting in living such a small life that I have time to fully engage with every single happening - I would like a machine to help me.