manhasnoname is right that we wouldn't use the present perfect with a time attribution, but that doesn't show why we use it here. Simple past can be used with or without a time attribution: "This morning, I ate waffles" or just "I ate waffles."
The reason we want present perfect here is that we are describing an accomplishment that extends into the present. We say "I have earned my Master's Degree" or "I have visited Asia" to show that this is something
...
The reason we want present perfect here is that we are describing an accomplishment that extends into the present. We say "I have earned my Master's Degree" or "I have visited Asia" to show that this is something
...
.jpg)
