That's the trouble. From an employee's perspective, I'd like a job with less than 40 hours per week (but also be paid lesson for it). But full working hours are favourable to employers.
You're right but I wouldn't like that even as an employee (which I am). Imagine your that your team triples in size and everyone is in some kind of part-time arrangement that makes it difficult to synchronize any kind of real-time communication. Horror.
It seems easy enough to agree some kind of core - "everyone comes in 2-4pm on Wednesday and we do any meetings then" or some such. I mean, all-remote teams manage to get work done.