This question looked interesting, and it's a matter of opinion but IMO none of them started out nearly as simply as we're discussing in this thread. I think they all fail the 4-weeks-to-revenue test (Not seeking to argue, was just curious).

Facebook is probably the simplest: one month initial development time, launching after that month, adding three more colleges the month after. It looks like they had funding within about five months. Maybe worth noting they're the most software-only of the bunch, and that the v1 product was a CRUD app with great market fit (that's a good thing here for velocity, I'm not downplaying their success). And especially when they were founded, revenue wasn't really seen as necessary, so they probably get a pass on the "be profitable in 4 weeks" bit.

Amazon did start out sort of simply, as a bookstore, but it took a year from incorporation to launch and Bezos had a significant investment from parents. Remember luck and survivor bias, they caught the dotcom boom and bust, too.

Apple sort of fits simplicity - you had a couple people who worked together before identifying the potential of a product, founded a company, and get to prototypes and incorporation in a few months. On the other hand I think it's a tough case for simplicity since step 1 is "Invent the Apple I" -- and make sure it's during the beginning of a new tech revolution. Plus, in terms of success we are probably talking about the Apple II, released the year after the I.

Netflix started with funding from a previous successful venture and right out of the gate needed to fund N copies of nearly 1,000 DVDs. Wikipedia suggests they had "only" 30 employees at the beginning. One of the cofounders had prior mail-order experience--which is great, and counts! But the post here concludes with "I'll try a new career in marketing;" I hope it works out for him but notice there's a trend of prior experience or domain knowledge through several of these companies.

Google was the result of a multi-year PhD project and involved coming up with a new ranking approach (or, for the detractors, adjusting and applying an existing mathematical concept to directed graphs) and a somewhat fresh take on search UI. Then later they had to figure out ads to turn a profit.

Adding the M, Microsoft was founded after Gates and Allen had already created a tech company together prior, and they saw a market opportunity. I'm sort of sketchy on the history, but a quick search shows they developed Altair BASIC in around four months, reusing some of the work they'd one prior, had the advantage of using Harvard's infrastructure at least briefly, and IIRC sort of pretended they had a product when they didn't. Paul Allen is said to have written the bootloader they'd need while on the flight to their sales pitch. Probably no wi-fi or laptops on board that flight :)

You could say they all pivoted at some point or didn't hit on what would be their full potential from the outset, so it's important to get going on something. At the same time, it seems they found one solid product and took a risk on it, rather than taking a shotgun approach and seeing what stuck.

Overall I think there's much more planning and medium- or long-term slog involved in these companies to say they started simply. Though for most small businesses I do agree with the sibling posts to get going and test things out ASAP. I think being aggressive about culling ideas that aren't working is ok for SaaS or CRUD businesses, so you don't risk becoming a zombie company.