It's one of those phrases "sell to buy" that everyone sort of latches onto and hates. Football clubs have to sell and have to buy. Actually selling players generates cash flow, and also helps the balance sheet enormously. If you are selling players for cash, you're doing something correct.
In defence of Brands, it's very difficult to move players on for a multitude of reasons, but most notably that we have overpaid for players that haven't worked out. The complaint for Brands, is in certain instances he has compounded an existing problem. Iwobi, Delph, Bernard and Gomes come to mind, and yes I appreciate Gomes had a serious injury but it's a big problem. Delph should never have got a 3 year deal. If he had the same deal as James, a 2 year + 1 option then we could have just moved him on this summer. Iwobi should not have got a 5 year deal, absolutely no way. Bernard should probably have only been a 3 year deal, or really a 2 + 1 as well. We've got into contracts we just can't get away from.
At present, unless we sell "upwards" we are going to struggle to sell anyone.