While it's true the Table has props.selectionData, the objects in that list contain only the data of the row, with no insight into the index of the row in the dataset/list.
Consider the following data value, where an object seems to be repeated:
[
{"name": "A", "value": 1},
{"name": "B", "value": 2},
{"name": "C", "value": 3},
{"name": "A", "value": 1}
]
If a user selects the last row of the data, how are you to know if props.selectionData represents the first or last row of data? Due to the complete dataset containing no guaranteed unique value, there is no way to perform something like an update query based on the provided data. FOr Perspective to expose which row is truly selected, we would need to inject some sort of index property, which would reflect the 0-based index of the row each entry in props.selectionData represents.
Now, here's the problem: what if users have prepared their data with an index key which actually means something to them?
# select * from MyTable where index<30;
[
{"index": 1, "name": "A", "value": 1},
{"index": 15, "name": "B", "value": 2},
{"index": 20, "name": "C", "value": 3},
{"index": 21, "name": "A", "value": 1}
]
If a user clicks the last row again, we can't run the risk of replacing 21 with 3.