Actually, it is a valid style of roleplaying. It's just not the style I chose for our Conan game. This element here is called Player Empowerment: the players are free, even encouraged to shape the world. TIt sounds like he didn't get the etiquette of gaming either. This can be innocent in a way but some players do kind of take fantasy to an extreme...
To be more precise, there are three "planes" in an RPG:
1. Character plane: The power to determine what a certain character attempts to do. ("I try to grapple him.")
2. Conflict plane: the power to determine events directly relating to the character ("I grab him and throw him through the window.")
3. Creative plane / director's plane: making statements unrelated to a character ("An Orc shows up.")
Classic distribution: Players influence only the 1st plane. The GM determines what happens, i.e. dictates planes 2 and 3.
Player Empowerment: the players may also influence the 2nd and sometimes 3rd planes to varying degrees. In the extreme, there is no single GM, but all players are GM at the same time.
There are also three basic types of Gamers, or let's say: Players with preferred playing styles. This is in RP theory known as "Threefold Model" (there are other, expanded models like fivefold, but this here is pretty commonly accepted):
Narrativist (NAR) - a.k.a. dramatist: this play style expects a satisfactory plot, and demands of a game system to give the players enough space to actively shape the story, rather than just experiencing it. The story as such may be epic drama, action-centered or even slapstick.
Gamist (GAM) - this style focuses on solving puzzles, fighting enemies and overcoming obstacles. This is about a fair competition between player and GM, revolving around combat, puzzles, schemes or mystical stories. The players' goal is "to win", i.e. solve problems, whereas it is the GM's job to make the competition as hard as possible while remaining manageable. It may be acceptable for players not to strictly separate player and character knowledge or abilities (e.g. an Int 4 fighter is allowed to solve a riddle if the player knows the answer).
Simulationist (SIM) - this style strongly emphasises internal logic of the game world and credibility of the story. As opposed to the Gamist approach, problems may not take place or be solved on the meta plane, but are resolved strictly within the game world, as realistically as possible.
It is all about simulating the reality of the game world and immersing in the other world, which is often significantly different from ours.
Thus, a SIM game often focuses on exploration of this foreign world.
Of course, many or most games cater better for one style than another. SIM gamers often prefer (or accept) rules-heavy systems. For example, in The Dark Eye 4th Ed, you have three and a half pages (!) regulating purchasing skills. In Conan, the matter is dealt with in 11 lines. You can imagine a Gamist is not going to be happy with TDE.
Also, IME many players change in their preferred style. Typically, many start as Gamists, then want something "more realistic" and become Simulationists, until at one point they may grow tired of that and morph into dramatists. Others are dramatists all the way. Actually I witnessed pretty much any change.
Personally, I want an internally consistent world (which is a SIM aspect) but I want rules to be quick, effective (which is GAM) and reliable (which is not NAR). I have some NAR aspects as well, but it is probably my least developed side.
Cast your vote on the poll if you like. And please share any thoughts you have on the subject.