On Noble, nothing is really that necessary. Of course, a Deity player would say that about my level too.
But the mythical typical Noble player (mythical, since typical people don't exist) underappreciates both workers and whipping.
While I'm frankly not certain whether food overflow from worker/settler builds is converted to hammers or converted into extra food for the next turn, but the fact is it's immaterial here, since whatever happens here, it will be happening regardless of whether you go over the top via whip, chop, both, or purely "naturally." So it's not an argument against worker/settler whips, and it's not a waste of food.
If your cities aren't growing quickly enough to renew working of resources after a whip, you may have settled them in an area without enough food. If they've got lots of food and they still spend a lot of post-whip turns not working high-yield tiles, then yes, the whip was unwise (the old guideline says simply, "Don't whip away resources" -- this handles most such cases). If they don't have enough food but they have enough hammers and they need to be where they are, then once again sure, don't whip.
Regarding Stonehenge: It definitely has its place in an opening strategy in a lot of starts, just like in a lot of other starts it doesn't. If you almost never build it, you should try building it in a few games where you otherwise wouldn't, before finally swinging back to a happy medium.
4 monuments isn't many monuments, and too little space for 4 cities post-Stonehenge is a really cramped start... if things are really that bad, then yeah, definitely rush instead. But what I was really getting at is specifically the synergy of CHA and Stonehenge -- besides the usual culture, monuments give CHA a +1 happiness, so you really do want them everywhere, unlike normal civs that might use religion, libraries, etc. for the pop instead after the first few monuments.
Rushes and harrassment vs. Stonehenge. Once again, I like rushes, rushes are good, when the opening situation is rush-friendly... but it often isn't (but this is partly a Noble/Monarch difference... and here for once I can actually from recent experience, as I spent some fun hours practicing Noble warrior rushes recently). I don't find harassment too effective in most cases, but where it *is* effective, I'd be fine with making do with my starting warrior or maybe one more until Stonehenge is done, if the starting position and my traits favored Stonehenge.
One thing you seem gloss over in the whole discussion is that Stonehenge produces its own culture, leading to a quick second capital pop, and that it produces GP GPP that can easily give you Theo or CoL, or a settled GP to fund your REX recovery. Don't treat Stonehenge as just a monument in every city, as that's shortchanging it!
Oracle for CoL (before I can afford the hammers for courthouses, and at the cost of not taking MC and not taking the no-Oracle option) to run Caste System just because it gains me the ability to run artists?! No thanks! If I've skipped Stonehenge (and I do skip it often), I'll send in a missionary or build the monument (an easy whip or chop) by hand, thank you! The handful of saved hammers from running the artist isn't worth running CS that early. CS is not really competitive with slavery until much later on -- until either Guilds or the time when you've set up the food end of a GP farm.
Also note that it's worth developing the skill of settling in ways that don't require quick pops, and this helps a Stonehenge strategy, since Stonehenge takes its time, as much as it does a "patchwork" strategy where each city gets its own solution.
