I'll echo the sibling comment by the TDB engineer, having read and contributed to similar systems myself.
Most of these custom databases (Influx) use techniques similar to TDB's under the hood, in order to persist the information in an read/write optimized way; they just don't "expose" it as clearly to the end-user, because they aren't offering a relational database.
A critical difference between the two, is that custom databases don't benefit from the fine-tuned performance characteristics of Postgres. So even though they're doing the same thing, they'll generally be doing it slower.
Most of these custom databases (Influx) use techniques similar to TDB's under the hood, in order to persist the information in an read/write optimized way; they just don't "expose" it as clearly to the end-user, because they aren't offering a relational database.
A critical difference between the two, is that custom databases don't benefit from the fine-tuned performance characteristics of Postgres. So even though they're doing the same thing, they'll generally be doing it slower.