I feel like as the game evolved to fit more of a trope-y Tolkienesque quasi-medieval setting it definitely got more and more out of place. 1e, especially earlier on, and before was much more of a genre mishmash. Fantasy in the truest sense.

We never combined them either but I did find it cool that the 1e DMG gave explicit advice on how to do so. Heck, there was even that one module where the characters can find laser weapons. [1]

[1] https://en.wikipedia.org/wiki/Expedition_to_the_Barrier_Peak...

> They have guns and smoke powder in 5e and it just doesn't feel right.

One of the settings for the game that became OD&D included far-future alien technology (Blackmoor), so there's long been precedent.