system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU, not necessarily Endgame] Would any of Tony's "Suit of Armor Around the World" initiatives have been sufficient to protect Earth?

Tony Stark's attempts at a Suit of Armor Around the World have had mixed results, to say the least.

The Iron Legion, which was his first attempt and a reaction to the Battle of New York, was destroyed during Iron Man 3, and reconstructed in time for Age of Ultron, whereafter it seems to have been dismantled.

Project Insight, which was developed in tandem with SHIELD, was co-opted by HYDRA, which resulted in the dissolution of SHIELD, reduction of its staff to a small team and a handful of vigilantes, and destruction of the Next Generation Helicarriers. 

Ultron, as we were shown, went full Terminator and became an existential threat in and of itself. 

Theoretically, these three programs would've worked in unison to defend the planet. Would any single, or combination of them, have been sufficient to defeat hostile forces? Namely, Thanos' invasions and attacks on Earth during Infinity War, but also, Dormammu's assault on Earth in Dr. Strange, the Wakandan  army if Killmonger's invasion had worked, and the Dark Elf attack on London.
gpt
Imagine hundreds or thousands of IM suits roving around at the same time- sounds great, right?

Now remember how when Pepper had Extremis the suits saw her as an enemy because Jarvis' friend-or-foe reasoning wasn't sophisticated enough to make the distinction between an enhanced combatant and an enhanced bystander.

His Ultron project would work, but there would be lots of collateral damage and the new threat that someone could hijack one of more of the suits. 

When Nick Fury recruited Stark he managed to override Jarvis, proving that there were known vulnerabilities in it that could be exploited and it would be hubris to assume there were no unknown vulnerabilities - something we know Stark is prone to.