Do you need to define DbSet's for all entitiies - entity-framework

Question

I am learning EF and unclear when to create a DbSet for an entity. In the standard Blog example that the Microsoft Docs have, they define DbSets for both Blog and Post. Why would one need to create a DbSet for Posts? Isn't the Posts accessible thru Blogs and therefore I can get the Posts using a LINQ query?
public DbSet<Blog> Blogs { get; set; }
public DbSet<Post> Posts { get; set; }
public class Blog
{
public int BlogId { get; set; }
public string Url { get; set; }
public int Rating { get; set; }
public List<Post> Posts { get; set; }
}
public class Post
{
public int PostId { get; set; }
public string Title { get; set; }
public string Content { get; set; }
public int BlogId { get; set; }
public Blog Blog { get; set; }
}

Answer 1

Why would one need to create a DbSet for Posts?
It's not strictly necessary. The rules in EF Core are:
By convention, types that are exposed in DbSet properties on your
context are included in your model. In addition, types that are
mentioned in the OnModelCreating method are also included. Finally,
any types that are found by recursively exploring the navigation
properties of discovered types are also included in the model.
Including & Excluding Types
But common practice is to declare a DbSet for each Entity because you might want to write a query that starts with Posts, or retrieve a single Post without its associated Blog.