[coolspot]

“client” here may refer to a backend app server. So you can have 10-100s of backend servers inserting into a same table without having a single authority coordinating IDs.

[morshu9001]

That table is still a single authority, isn't it? But I guess fewer steps is still faster.

[tracker1]

Except if you're using a sharding or clustering database system, where the record itself may be stored to separate servers as well as the key generation itself.