Reading between the lines, the constraint is that today’s chargers are always monotonically increasing state of charge with a roughly steady DC applied current

Reading between the lines, the constraint is that today’s chargers are always monotonically increasing state of charge with a roughly steady DC applied current (tapering slightly at the high end). Adding in something like pulsed charging or even some reverse-voltage segments could potentially change the charging dynamics enough to let the battery charge much faster without damage.