Choosing between a platform and a custom build
The question is not which is better. It is which constraints you are willing to live inside, and for how long.
Platform versus custom is usually argued as a technical decision. It is really a question about where you want your constraints to sit.
A platform gives you a floor
Hosting, payments, security updates, an admin interface and a plugin ecosystem arrive on day one. That floor is worth a great deal when your product is fairly conventional and your differentiation lies in merchandising, service or brand.
The cost is a ceiling. When a requirement falls outside what the platform imagines, the workaround is usually more expensive than the feature would have been in a system you controlled.
A custom build gives you a ceiling
Nothing is impossible, but nothing is free either. You own the parts a platform would have given you: the admin, the integrations, the upgrade path, the security posture.
Questions that decide it
Is the thing that makes you money a standard pattern, or an unusual one?
How often will the model change — products, pricing, fulfilment?
Who maintains this in two years, and what are they comfortable with?
What happens if the platform changes its terms or its roadmap?
A good answer often sits in between: a platform for the transactional core, custom work at the edges where the business is genuinely different.