This is not so. VAT on inputs ( puchases of materials and services but not labor) to a business entity can be offset against VAT liablity on outputs( Sales). This works all the way through the production chain until the tax falls on the final consumer. The net effect is almost exactly the same as a sales tax.
Incidentally no system of taxation is going to do away with the IRS or something similar.Once you have a tax you will need an enforcement organisation no matter what.
The flat tax rate can be increased just as easily as a sales tax. My preference is for a National Sales Tax or VAT because they reward the more efficient organisations. A tax on profits is a penalty on the most efficient organisations. Another advantage of a NST or VAT is that it puts US manufacturers on the same footing as foreign producers in our domestic markets.
You can construct a VAT to work in either fashion, tax-on-tax or input-only. US gov'ts at all levels are thoroughly addicted to the present-day tax-on-tax schemes in place throughout the nation, and there is no plausible reason to suppose that the greedy hands of the Regress will design anything other than a tax-on-tax VAT scheme.
Proofreading is our friend (sigh).