These figures actually show that management has been the real issue, not finances.
2% dividends is nothing in the grand scheme of things. It has had no bearing over the club's ability to succeed. 10% on interest is more substantial, but, again, it is not the reason why we have failed in the last 8 years. With the debt repayments, that is 16% overall (rounding to 1dp, it is 15.6%). So, 84% is still spent on the club.
Net player purchases is a bit of a flimsy argument to level 'payments to Glazers' with 'investments in players'. In the end, cash from player sales isn't specifically held to pay for players, so it makes no sense. Some of that could have actually been used to pay dividend or expenses etc. In the end, 1.4bn has been spent on players no matter how you twist it.
The 16% is not the reason the club is currently in the position it is. The main problem is bad investments and overpaying of wages. Correct these and people probably won't even notice the owners.