How is the technical interview process valuable _for companies_ at this point when it seems to be evaluating how well you can prepare for their specific leetcode interview, and how well you practice the incantation of the system design problem (make sure you follow the template and the pattern!) - do they really think they're selecting the best candidates, and not the most practiced interviewers?
Beyond the barest basics, 99% of the time the only thing that's genuinely relevant is whether or not the team wants to work with the candidate. Almost nothing else that is relevant is even knowable until after they're actually working. Exceptions only prove the rule.
It's a sham but I guess it makes someone feel like they've contributed value somehow.
Also note that the OP said they found the coding questions were mostly easy/easier than they expected so maybe the amount of work required (for older/more experienced candidates) on preparation is not so high? I dunno.