This logic is worse than strawman. You build a business that 100% depends on facebook. Facebook is a commercial company. At any point they can shut it down, an

This logic is worse than strawman. You build a business that 100% depends on facebook. Facebook is a commercial company. At any point they can shut it down, and you are back to 0. Bad. You build a website that depends on "a browser". There are at least 4 popular browsers desktop browsers, with several variations on mobile and more exotic browsers. All 4 are run by different companies. For most websites you would still function if even 3 of the 4 major browsers were shut down. Furthermore, desktop software is downloaded and cannot just vanish (let's ignore app store and that kind of magic, as not all browsers come in like that). So I think you just proved the point on writing a "website" is a safer bet then writing a "tool for facebook"