So you break scrolling for a very large number of users because it looks marginally prettier? That's, like, the literal opposite of proper software design.
Reality check: not a single user gives a damn about the pretty scrollbar. They care about being able to use the site. Breaking the latter in order to achieve the former does the precise opposite of what you intend: it weakens your brand because users associate it with broken websites.
This isn't to mention that a user might very well have a system scrollbar set for usability reasons (perhaps with a more-visible - whether better contrasted or simply bigger - slider due to poor vision, or an oversized slider due to poor motor skills), which means that your prioritization of "brand" over function is effectively giving the middle finger to people with disabilities. Nice going.
Reality check: not a single user gives a damn about the pretty scrollbar. They care about being able to use the site. Breaking the latter in order to achieve the former does the precise opposite of what you intend: it weakens your brand because users associate it with broken websites.
This isn't to mention that a user might very well have a system scrollbar set for usability reasons (perhaps with a more-visible - whether better contrasted or simply bigger - slider due to poor vision, or an oversized slider due to poor motor skills), which means that your prioritization of "brand" over function is effectively giving the middle finger to people with disabilities. Nice going.