What do you mean? Credit rating agencies are not regulators. Plus, pretty strict regulations around credit ratings and their essential role in portfolio composition were already in place at the time. In fact you could arguably say that they were actually one of the reasons behind the severity of the crisis.
And even if we put aside that very glaring error aside, if your comment was true Scandinavia or some parts of Europe would've a lot more multinationals than the US, since their corporate tax rates are already lower than in the US. You can also take for example, Spain which has had a ~similar tax rate than the US before 2017, why don't they have a bigger economy per capita if it was that easy and countries were competing to lower taxes?
Corporations aren't individuals btw, and taxing the dividends or capital gains is much more efficient. Eventually, any money you don't tax from a corporation usually flows back to the investors in one way or another. So even if you want higher taxes, corporate taxation is usually just something that "sounds good" or is knee jerk reaction to "stick it" to the big corps rather than to actually get more tax revenue.
