If your client is a big company they can blackmail you to have a "VAT discount". If you want to do business with them, you'll need either to eat their VAT with a percentage of your expected benefits, or you are obliged to cheat to survive. You end figthing with your clients for paying the damned VAT. Always. With each one.
If you take in mind all the lost work hours, angry clients and nuissances that causes to everybody it is clear that is worthless and hurts the economy, but the problem is that VAT is like cocaine for the government. Is wonderful and they always want more. With VAT you can bill taxes to children and to elders for the privilege of buying something in your city but you are not obliged to provide them with a future pension, or any other service instead.
And like any other drug, you raise and raise the doses until finally all collapses. You want to raise VAT and bill 21% for a book or a film? Not problem, people can survive without going to cinema or buying a book. Now you have a 21% of 5 tickets, instead a 4% of 500 tickets and so.