Messenger does 3 things right:

1. Being able to discover people by name / surname, no phone number necessary. This is the most important privacy feature people care about, it's ironic that Meta had it from the get-go, while other platforms have barely caught up.

2. Used to have frictionless message sync, including in the event of a catastrophic loss of all devices, which put it far ahead of most apps (sadly nerfed by E2E).

3. A much better group implementation than Whatsapp / iMessage (no need to maintain a contacts list, no need to share phone numbers with everybody, you know who everybody is by name and surname). This is perfect for semi-professional groups where people are acquainted but not close with each other, especially when some members hold positions of power and don't wish to receive calls from irate people). Parents / teachers or blue-collar coworkers are perfect examples.

It's sad that all these apps are converging on the same set of features and mis-features, with nobody (except Telegram) really exploring the tradeoff space any more.

The base tech of a "friend discovery network" isn't "hard" in the grand scheme of things. But getting those who don't put much thought into their tech to care enough to move out takes a gargantuan effort. Musk had to go full nazi to start seeing the bluesky adoption, and it still isn't the level of catastropic effect you'd think would happen if you heard about this 20 years prior.

Before Zuckerberg loosened the moderation rules in Trump's favor he tightened them in favor of anti-Trump forces (and even using the terms "loosened" and "tightened" is assuming a frame that online speech that politically-benefits Trump in some way is inherently more worthy of moderation than speech that politically-harms Trump, which is itself an object-level political stance).

It's probably a mistake to characterize that as "Zuckerberg" himself making a decision - the sorts of people who worked at Facebook in the mid-2010s were overwhelmingly Democrats or Democrat-aligned people who found the sorts of things that Trump was saying, and that Trump's supporters were saying, immoral and horrifying; and often felt they had a moral duty to censor this speech on their platform in the name of protecting people they considered marginalized. This didn't necessarily need Zuckerberg's involvement himself, and I think he may have personally changed his mind about Meta's moderation policy during the Biden administration, although of course it's hard to be sure what is actually going on in the head of any specific public figure.

Trump is making a point of putting allies in high positions at Meta because in general it's now clear to everyone in American politics that being able to control the moderation policy of major social media platforms is politically important; because those platforms are where people who vote or otherwise make policy in your country do it. Every future administration in the US will attempt to do the same thing - the details might differ as the landscape of social media changes - and every single one will claim to be acting in the name of authentic free speech and safe, reasonable discourse.

I wish that practical free-software alternatives to every proprietary social media network were available, that by construction had no central organization that could be targeted by any branch of government to censor political speech. This is unfortunately a difficult technological and social problem to solve; we have a bunch of half-solutions that very few people actually use, and the bulk of the population continues to communicate on proprietary social media platforms.