With the exception of the assumed choke, which you use, but which was not part of the original circuit, I agree. However, since the idea was to put is something that isolates the rather large currents flowing in the MAX232 from the remainder of the circuit. Most of this current should flow in the bypass cap provided at the Vcc and Gnd pins, the current will follow the path of least resistance.

Now, if there's a resistor, which almost everyone building a circuit at home has, rather than a choke/ferrite-bead, which few people have lying about at home, put in series with the Vcc connection to that bypass cap, and bypassed on the system side of the resistor, with yet another cap, then the only difference in impedance between the two cap's is the resistance in the GND rail, between the two cap's. When current needs to flow from the MAX232-local cap into the GND pin, it flows from the cap, through the ESR of the cap, but when current needs to flow from the MAX232 GND pin into the cap(s) it sees the ESR of the remote cap in series with whatever resistance there is in the GND path. It also sees the ESR of the local cap. Since the local cap alone is a lower impedance, the bulk of the current flows there. The result is that more of the noise-current flows through the local cap, attached directly to the MAX232 than through the remote cap, separated from the MAX232 by that resistance. If even a very small part of that total resistance is in the GND path between the two bypass cap's, then much less current will flow through the R in the GND rail than through the local cap.

As you've stated, the same current needs to flow through both Gnd and Vcc. The current from Vcc and Gnd is smoothed by the cap's and the surges are circulated by the local cap, thereby significantly reducing what flows through the global supply rails.

There's no question that a lossy ferrite bead is a MUCH better solution. Most people don't have an assortment of ferrite beads on hand, though. Knowing that a ferrite bead is better, one might still be inclined to try something that can be done with what one has on hand. If that's shown to be an overall improvement, the ferrite can be ordered and used later.

RE