Kafla, look away....Here comes a techie post!
Clipping: I have read about this, studied and debated during my Uni days, heard many opinions and tried to absorb as much of the Science as I can. As you correctly say Kafla, there are many conflicting views out there and even now I am learning. As such, do not take this as gospel, just the amalgamation of my learning so far...
Bottom line...
Clipping is bad
Digital flat-lining is bad sound. It sounds granulated and uncomfortable, especially on good headphones/speakers. Badly set output levels and/or compressors during production are the main culprits for these sounds. During the peak of the loudness race (late 90's, early 00's), and (perhaps coincidentally, perhaps not...)before the advent of the extra headroom 24BIT and 32FLOAT provided mastering engineers, clipping became an issue for many well known commercial releases. Oasis "Be Here Now". RHCP "Californication. Two albums I cannot touch as they were RUINED at the master stage.
Do they damage my headphones/speakers? Perhaps. Maybe. Slowly. Over time. Fully peaked "flatlined" sound puts speaker drivers at fully pelt, for extended periods. This is potentially a risk, dependant on how resilient the sound source is.
Over and above anything, Clipped sounds SOUND bad. They are hugely annoying to anyone with an ear for it.
The big place clipping is of risk to speakers is actually during the production phase. In studio speaker monitors. Also guitar/bass/PA amps...
I have had to replace three bass amp speakers in the last 9 months due to customers setting the input drive to 10, and playing too hard (I decided enough was enough. Sold the amps and replaced with amps with 3 times the power: no need to push them so hard now!). Clipped bass frequencies are notoriously bad apparenly...
PA speakers, Studio monitors, etc, often have limiters inside that refuse to play clipped sounds.
When the sound source is the studio mixer, the 0db limit of home listening systems do not apply, so they can be pushed past the red, with damaging sound a clear risk. My Mackie speakers "dim" their sound momentarily when a clipped sound is sent thru them, in a self-protecting mechanism. Clever stuff.
As such, it was drilled into me at college/Uni to always, always avoid clipping in all circumstances. The best way to protect ears, speakers, and to maintain a higher standard of sound in general
I repeat. Do not read the above as gospel. Yes, I do this for a living but I have holes in my knowledge and the technical nitty gritty is not my forte, I will admit this. I am much more the creative producer type than the science guy. I do admire their commitment, it just isn't me.
I hope the above makes at least some sense