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You can really tell that they wrote parts of the module before publishing the rules…
(ttrpg.network)
For reference: There is a duell in the module where a shaman tries to secretly help one NPC by continously casting Cure Wounds on him while supposedly only helping him "stand up" after he intentionally let‘s himself fall prone. To spot this, a PC has to specifically declare checking for interventions a then suceed a DC 15 perception-check despite being within earshot…
I tend to rule that any components are "assumed to be in the materials pouch", unless there is a significant (relative to party wealth) gold price attached, in which case they need to be bought. In practice I found that only really seems to apply to resurrection spells.
From there, the only thing that matters to me is can you reasonably perform or (roll to hide to perform) the semantic and vocal components, as well as get out the materials of your materials pouch in your current state.
In practice this means I can ignore components 85% of the time, but can still temporarily de-power my players if needed for some reason.
your first paragraph is literally the book rules for spell components. You either have a focus/components pouch for mundane components and anything with a gold amount needs to be spent to cast.
Very few spells actually have a costly material component for it to ever come up anyway.
Can't hide somatic or verbal components without being a Sorcerer for the meta magic though. Otherwise you're literally undermining one of the key features of that class.
Spell components exist literally for the reason stated at the end: so the DM can keep in check the power of the spellcaster as needed for the scenario by limiting what spells are available to be cast.
Identify - (a pearl worth 100+ GP) Spend 100GP to fine out what this 10GP sword does.
The pearl does not get consumed though. Buy it once, use it indefinetly.