It's simply another solution. You have to organize tax system in some way, and there are many ways to achieve that.
The main idea behind VAT tax is that you never pay it twice. You're obliged to pay the VAT as soon as you have issued an invoice, but you can substract from that sum the VAT you've paid to you supplier etc.
There are 2 alternate solution, paying a tax based on sales - than each time the product changes the owner, the tax have to be paid in full sum. Such solution makes outsourcing less profitable, and long supplier chains completely unprofitable.
Second is to tax only when the product is sold to private person - end consumer. It promotes outsourcing, such as VAT, but the problem is as long as the good is in storage, the tax is not paid.
VAT joins the benefits on both of those systems. The tax is never paid twice, but it is paid on each production level as soon as the invoice is issued, so it provides constant cash flow to the government.
You're asking for benefits only, but there are also big disadvantages. VAT is relatively easy to collect, but expensive to pay - because of the complications, many even small companies are forced to hire an accountant. It is also vulnerable to fake invoices, there are organised crime groups which are specialized in taking money from government because of fake invoices - because VAT works so, that if you have paid to you contrahents more as you are about to pay, the government pays you back the difference.