One of the biggest advantages of the Rouge is the ability to switch hit. By which I mean that they can work in melee and at ranged with (near) equal benefit, allowing you to be wherever you need to be for optimal benefit.Those rogue guides might well mention dual wielding melee as a possibility, but they should not recommend it.
As a rogue you're soft and squishy. If possible, stay out of melee and let the tanks soak the damage.
You won't be dual wielding, but you should find it relatively easy to get the next best thing: attacking with advantage also allows you to roll two dice to increase your chance of delivering your sneak damage.
As for TWF Rogues, it partially depends on group dynamic, level, and the DM. Optimally, you want to hit with your main attack, then retreat with your bonus action (limiting attacks against you). TWF gives you the choice to risk attacks in an attempt to get your Sneak Attack off if you miss with your main hand. At lower levels, this is much harder, because your AC probably isn't that great and neither are your HP. Once you get Uncanny Dodge (or Evasion, I forget which), you can use your Reaction to half the damage of one attack, making TWF much better. Of course, if the DM is vindictive and targets the rogue repeatedly, then TWF is a bad choice in that game.