"Loopholes" are often things that benefit society though. It's sort of an indirect tax. Like donating to a charity. Basically the government is saying that they'll lower your tax burden if you use your money in a way that benefits society as a whole instead of just enriching yourself.

Thing is, the very existence of a company benefits society as a whole: it produces and trades goods that people need and want, and also gives stable source of income for sometimes dozen thousands of its employees.

That's why we should be carefull with excessive taxes for bussiness - if some companies go bankrupt, or lay off 20% of their workforce as a result it might be a net loss to society.

And before you start arguing that sometimes companies make money on shady things: yes, they do, but then you don't punish them for that with taxes, there are criminal laws for such things.

There are thousands are companies that exist solely as a tax dodge for some other company or in order to prevent paying workers at a different company. Some companies exist to just play games with money on the market, which has at best only very indirect benefit to the society as a whole and has a definite chance of being a harm to society. Some companies exist simply to drain all of the money out of other companies before they go bankrupt.

None of this is illegal, but it's hard to argue a benefit to society in general.

Each loophole has a base, people who care deeply about it. Against this is a vast population that doesn't even know it exists. Closing each loophole is an enormous political battle with very little payoff in tax revenue. If you add a new tax bracket or raise the capital gains tax, you get much more revenue for the same political lift. This is setting aside the marginal value of a dollar for the different populations taxed and the effect of economic inequality on corruption, democratic institutions, and social cohesion.