I mostly disagree with your inequalities. Sure, in a literal sense, they are not equivalencies, but I think often they'd be a fine substitute. It doesn't really matter that the "very old" 200-year-old house" isn't literally "ancient". It doesn't really matter that the kitchen counter you just intensely scrubbed doesn't literally reflect light in a sparkly, flashy way. Exaggeration and hyperbole are valid rhetorical devices, and, given context, the listener or reader will understand what is meant.
Sure, "bleak" doesn't work for "very dark" when you're talking about a literal lack of light, but it would probably work when describing a certain type of film, or an awful situation. I don't think the site is trying to say "every time you want to use 'very dark', use 'bleak' instead"; it's just trying to give you alternatives that might -- but might not -- fit the usage you're looking for.
Beyond that, I do agree with the overall motive here: "very" is often a lazy intensifier, when we could be much more expressive in our speech or (especially) writing. For all its faults, the English language does offer decent breadth when it comes to synonyms of various intensity.
Sure, "bleak" doesn't work for "very dark" when you're talking about a literal lack of light, but it would probably work when describing a certain type of film, or an awful situation. I don't think the site is trying to say "every time you want to use 'very dark', use 'bleak' instead"; it's just trying to give you alternatives that might -- but might not -- fit the usage you're looking for.
Beyond that, I do agree with the overall motive here: "very" is often a lazy intensifier, when we could be much more expressive in our speech or (especially) writing. For all its faults, the English language does offer decent breadth when it comes to synonyms of various intensity.