Why is it unsound to treat every profit as riba merely because riba is linked linguistically to increase?

Khafi, Mushkal, Mujmal and Mutashabih: Degrees of Obscurity

• The legal sense involves a particular kind of excess, delimited by evidence
• Because the Qur’an permits riba
• Because riba has no linguistic link to increase
• Because every sale is inherently mutashabih