Most companies tend to avoid fluctuations. Companies will sell most of their BTC holding if price were to drop significantly
Most companies do aware of it but the fact is that BTC is not actually usefull in most of the companies sale as most people still dont have any knowledge yet of BTC . This will hinder their sale if they were to only accept BTC, that is why most companies that accept BTC accept FIAT as well, this makes BTC not usefull as things could be purchase with FIAT rather than BTC.
Also that Microsoft do accept BTC for some sale but it has yet make any significant effect so it is not a guarantee that if a big company was to accept BTC then it will make a significant effect
True, most aren't ready yet to accept BTC only, it would be like being in 1990 and acceping electronic email only and ditching paper mail. Time will come, we are just still 10+ years from that tho.
Some have found a niche and are making great BTC only, namely amagimetals, they went BTC only and the business is going smooth.