As an investor you pay taxes on your net annual capital gains and losses can be used to balance gains.
False, as specified by the next statement, you can only deduct a maximum of $3000 in losses.
"If your capital losses exceed your capital gains, the amount of the excess loss that can be claimed is the lesser of $3,000, ($1,500 if you are married filing separately)"
So the maximum loss you can deduct in any given year is 3000.
And in fact Dividends on corporate investments are paid on net profits after the corporate tax rate has been been deducted. That's what dividends are, sharing net profits with shareholder.