EdgeDB employee here. I couldn't have asked for a better question to demonstrate the power of subqueries! Here's how I'd do this in EdgeQL:

  with tag_names := {"angular", "nestjs", "cypress", "nx"},
  select BlogPost {
    title,
    tag_names := .tags.name,
    match_count := count((select .tags filter .name in tag_names))
  }
  order by .match_count desc;

Which would give you a result like this:

  [
    {
      title: 'All the frameworks!',
      tag_names: ['angular', 'nestjs', 'cypress', 'nx'],
      match_count: 4,
    },
    {
      title: 'Nest + Cypress',
      tag_names: ['nestjs', 'cypress'],
      match_count: 2,
    },
    {
      title: 'NX is cool',
      tag_names: ['nx'],
      match_count: 1,
    },
  ];