If you read the agile manifesto, there are no specifically prescribed steps or rituals, and in my experience, most teams implementation of scrum is entirely counterproductive to actually being agile. The core tenet of being agile is essentially people over process, and things like daily stand-ups, extremely formulaic retrospectives and backlog grooming meetings do nothing to empower the people and allow them to be truly agile.
It's supposed to be "people over process", yet most "scrum" is all about process: too many meetings and other assorted bullshit like filling out your sprint planning and retrospective report every 2 weeks.
Scrum is about getting people to talk to each other and that's what all the process is about. If you already have good communication between developers and those making the business decisions, then sure scrum is probably a waste. Places that actually have that communication without having scrum force those people into a room aren't common. It's also common that places that don't really do scrum don't have empowered PO's or devs, so the meetings are wasted time.
Yeah, but devs can be finicky about waking up early. Half my team was fine with 9am and the other half preferred working more of a 11am-7pm shift. We experimented with asynch Slack standup but it fizzled out after a few weeks.
Most of my teams problems with Agile/SCRUM come down to skipping steps or not following best practices. Once we fix those, it gets better.