what will happen if we do not wrap the client component with hydrate client?

import { trpc } from '~/trpc/server';
import { ClientGreeting } from './client-greeting';

export default async function Home() {
  void trpc.hello.prefetch();

  return (
    <HydrateClient>
      <div>...</div>
      {/** ... */}
      <ClientGreeting />
    </HydrateClient>
  );
}