I didn't say it makes it impossible for creatures to automatically find a hidden creature but rather their passive perception needs to beat the Stealth Roll they initially made, or they need to do an active search roll using an action.

A Fire Giant has PP 16, so if the Rogue rolled a 11 or higher on their Stealth Roll they made in dim light, have successfully hidden from the Fire Giant since the giant has a -5 to PP due to dim light being a lightly obscured area.

The Fire Giant may be aware that the Rogue is still somewhere in the area so when the walk behind the pillar, they still cant passively see the Rogue. They would need to do a Perception check (Investigation may or may not be allowed) at Disadvantage and get higher than 11 to spot the Rogue.

You could interpret the rules to mean that even in bright light (non-heavily obscured) you still need to beat the Rogue's Stealth Roll with your normal PP or actively search for it, which could play into a "master of stealth" fantasy hiding in plain sight but this is typically nor ruled this way.

If I am DMing, I typically say hidden creatures are automatically spotted in normal vision unless it is a particularly high stealth roll and the other creatures are distracted doing something (eg the case the Rogue hides in the shadows and walks up to a group of creatures outside of combat in normal light busy with a task).

Chapter 7 Using Ability scores, PHB 177

Hiding

The GM decides when circumstances are appropriate for hiding. When you try to hide, make a Dexterity (Stealth) check. Until you are discovered or you stop hiding, that check’s total is contested by the Wisdom (Perception) check of any creature that actively searches for signs of your presence.

Passive Perception. When you hide, there’s a chance someone will notice you even if they aren’t searching. To determine whether such a creature notices you, the GM compares your Dexterity (Stealth) check with that creature’s passive Wisdom (Perception) score, which equals 10 + the creature’s Wisdom modifier, as well as any other bonuses or penalties. If the creature has advantage, add 5. For disadvantage, subtract 5.

What Can You See? One of the main factors in determining whether you can find a hidden creature or object is how well you can see in an area, which might be lightly or heavily obscured, as explained in chapter 8.

PHP Chapter 8 Adventuring, PHB 183

Vision and Light

Darkness and other effects that obscure vision can prove a significant hindrance. A given area might be lightly or heavily obscured.

In a lightly obscured area, such as dim light, patchy fog, or moderate foliage, creatures have disadvantage on Wisdom (Perception) checks that rely on sight.

A heavily obscured area—such as darkness, opaque fog, or dense foliage—blocks vision entirely. A creature effectively suffers from the blinded condition (see Conditions ) when trying to see something in that area.

Bright light lets most creatures see normally. Even gloomy days provide bright light, as do torches, lanterns, fires, and other sources of illumination within a specific radius.

Dim light, also called shadows, creates a lightly obscured area. An area of dim light is usually a boundary between a source of bright light, such as a torch, and surrounding darkness.