Comment by xp84

Good question.

I feel that when a company is in a super dominant, dare I say monopoly position (Google Search is the most obvious example) with one of its product lines, it usually is destructive to free markets when they aim the money firehose at another, money-losing product. It does this by driving out competition against that second product, which results in less choice for consumers.

I don't think it's necessarily a problem when a company that isn't a monopoly subsidizes another product. I agree that's pretty normal.