It's not async vs sync thing, it's that you're perverting stand-up from a tedious but low-stakes collaborative process (hey, what's everyone working on, who can help me with this quick problem...) to a grueling and ruthless micromanagement process that gives you false metrics to judge your employees by. It's a sign that you don't really care about your people or your team or their morale and just want to find easy numbers to evaluate people by, the engineering equivalent of "you're fired because you clocked in three minutes late four times this year". It's totally irrelevant to the job at hand...

Yeesh, it scares me that there are people like you who actually think this is a good management style. It's not even a management style, it's just petty sadism. Please seriously consider another career, this is not good for anyone on your team. Sorry to be so harsh, but god damn, this is one of the most braindead, heartbreaking, soulsucking posts I've ever seen on HN. Your team deserves a better manager than you.