Many everyday group structures — classroom exercises, brainstorming sessions, fast-paced meetings — are built in a way that systematically rewards speed and volume of verbal participation over the actual quality of an idea, which means a genuinely good contribution from someone who thinks before speaking can be reliably overridden by a faster, louder, less carefully considered one. This isn't a flaw in the quiet person's thinking — it's a structural feature of how the interaction is set up, rewarding a specific performance style rather than the substance of what's said.
The fix isn't necessarily asking quiet participants to become faster and louder — it's recognizing that group structures can be deliberately designed to surface good ideas regardless of how quickly or loudly they're delivered, which benefits not just introverted participants but the actual quality of the group's output.