The implication of her article is that they’d have a hard time raising that money and/or that they somehow aren’t doing well - I don’t see any evidence of this cited anywhere in her post.
No, the implication is that raising such a high level of VC would put huge pressure on Substack to grow and enshittify, thereby ruining the platform for writers who currently think it's good.
In other words, their current business model does not support their valuation, which necessitates a pivot.
In other words, their current business model does not support their valuation, which necessitates a pivot.