Earlier quoted context omitted.
Yes, this is an aspect of orbital mechanics that people find unintuitive before they study it. You can't be captured by a planet's gravity alone. If you come in from infinity (i.e., not already captured) you will escape to infinity (remain not captured). The basic idea can be seen from the fact that gravitational dynamics are time-reversible, so if gravity could capture you like this you could also start in orbit aro…
It can reduce the delta-V requirements, though - by the same principles as a gravity assist, a capture burn (especially into a loosely-bound planet-centric orbit) often takes less work than burning into the equivalent heliocentric orbit on your own.
Note to the audience: these mechanisms don’t violate the conservation of energy because you aren’t tapping the object’s gravitational energy per se but instead its orbital energy around the sun. Put another way, you can’t do a gravity assist or capture burn in any direction.