You could stitch this together yourself. That was never the question.
You're capable of wiring a ticketing tool to a CFP form to a shared spreadsheet for
vendors, and plenty of organizers do exactly that. The real question is whether
being the maintenance crew for that stack is how you want to spend the event. A chef
who spends the night fixing a cooking robot has stopped cooking — your craft is the
event, not the glue between the tools that run it.
Fomomento carries the plumbing: the schedule kept in sync with the people attached to
it, UK and EU VAT kept correct as the rules change, and gap-free invoices your
accountant and tax office will accept. The control stays yours; the maintenance
doesn't.