[spikels]

Idea is to prevent people from offsetting large incomes with capital losses. This simply appears unfair to many - earning lots of income but paying little tax.

A more sophisticated argument is that since you can control capital losses by choosing which assets to sell you would be able to manage your taxes. With enough assets and some planning you could never pay taxes despite having a large income.

The $3,000 cap prevents this. Similar approaches are used throughout the tax code to prevent abuses.