The method arg of parameter macro is used to solve conflicts with existing methods on the spec context. This works well when you define the value for method arg.
When the specified method is not defined, the original param name is used.

In the example below, the current behavior raises 'No response yet' because status is a reserved method of rack test.

get '/foo' do
  parameter :status, "Blah", method: :status_param # this param is not required
  example 'meh' do
    expect(status).to eq 200
  end
end

The PR removes the fallback that looks for the original param name when the provided method is not implemented.

More context here: #312 (comment)