The case study here is Facebook introducing the ability to schedule posts in Facebook directly, theoretically hurting Buffer et al.
Take a look at Buffer's publicly-available revenue data [1]. Can you see when this change occurred?
In general, by lowering the barriers to entry into an activity, MORE people participate in it. This makes the general market larger. A portion of those users have a measure of success and end up wanting more advanced functionality, so they move to a tool that will give them more advanced functionality.
In this case: Stripe Payment Links will enable a lot more people to conduct ecommerce, most of who would never have tried. Some of those people will be successful, find that ecommerce merchants need a lot of tools to manage their businesses, and will acquire those tools.
I believe this is good news for Shopify, rather than bad.