Why use serverless-plugin-aws-alerts?

IIUC

only tests lambda metrics, which is kindof pointless for HTTP aka AWS/ApiGateway.

I was looking for a help to help setup alarms, and it seems easiest just to do it via resources, e.g.

resources:
  Resources:
    NotifyMe:
      Type: AWS::SNS::Topic
      Properties:
        TopicName: ${self:service}-NotifyMe

    Api5xxAlarm:
      Type: AWS::CloudWatch::Alarm
      Properties:
        Namespace: AWS/ApiGateway
        MetricName: 5XXError
        Dimensions:
          - Name: ApiName
            Value: ${self:provider.stage}-${self:service}
        Statistic: Sum
        ComparisonOperator: GreaterThanThreshold
        Threshold: 0
        Period: 60
        EvaluationPeriods: 1
        AlarmActions:
          - Ref: NotifyMe

Am I missing something?