Because there is a standard way for people to make their consent known. Just because you ignore someone withholding you consent doesn’t mean you are free morally.
Every web request costs someone money. If you aren’t paying them you are being provided a service. They’ve given you knowledge/ material in their possession free of charge. You are taking advantage of that good will by using the content for purposes not intended. That is a moral failing.
To be clear the ownership of the material is not important, just the access is immoral, as the harm is already done.
Ill add the caveat that it can be moral if they’ve specifically told you you can via the websites robot.txt file which websites of consequence all have. But the assumption has to be they don’t intend this because that is how consent works.
For everyone with a peloton, you can flash the bike with an aftermarket software.