I once worked in the prototype lab of a very well known company that designed audio and television equipment and I can assure you speaker/amplifier matching is well known and understood.
Designing speakers that would clip (bottom out) and not self destruct happens all the time, it's a non issue as it doesn't really cost much extra (essentially nothing with small speakers).
The real issue is that some manufacturers started to use second rate products then they all followed suit—even those with 'named' brands that one paid extra for (but who got little in return).
The real problem was that both users and equipment reviewers didn't complain (or they didn't do so with sufficient vigor) and manufacturers let it slip, which was easy given the highly competitive nature of laptops where manufacturing cost are important.
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Edit: I should add that this was rarely an issue in the past when substabtial gain reserves were a normal feature in equipment. Although it was occasionally a problem in high powered HiFi equipment, it was essentially never so in domestic radio sets. The question remains — then why is it now a problem in laptops?