I've often thought that, looking historically, Notion only exists because product innovation in Google Docs is decoupled from revenue growth for Google Workspace. Putting a draggable handle, at the user's election, alongside every paragraph in Docs, and adding a customizable shortcut for search across docs, would go a long way towards Docs being 90% of what Notion's value proposition was as of a few years ago. But most startups using Notion already had Google Workspace for email anyways, so there was no growth story there for Google to invest in this mandate.
Now, Notion's done a lot since then. If you want a knowledge base that can also have semi-structured tabular data, and portability in that data, it's hard to beat. Notion AI, pulling from disparate sources with the context of the current planning document, is really neat, too! But not every company will want to pay the per-head cost for this, unless it can replace other existing tools.
And when it comes to spaces like CRM in that context, looking at https://www.google.com/search?q=notion+crm&udm=14 ... there's a lot that could be said about Notion's (lack of) SEO/advertising there, but more concretely, a CRM solution nowadays has to bring a wealth of integrations as a near-prerequisite, and Notion doesn't have a mature story there - nor can they easily, because different customers will have different data models that make it hard to have a standardized notion of "what fields can I count on to be present for an Account."
Notion is a really powerful system. If it didn't already have a $10B valuation, it would be in tremendously good shape. But it has a long way to go to find the areas of growth it needs to grow beyond $10B.