Table alias ignored for columns specified in INSERT statement in SQL Server

I saw above question in one of the blogs. But couldn't find the answer anywhere. Maybe SQL Server experts here can help me on this.

CREATE TABLE #DEMO (VALUE1 INT, VALUE2 VARCHAR(10))

CREATE TABLE #DEMO1 (VALUE1 INT, VALUE2 VARCHAR(10))

INSERT INTO #DEMO VALUES (1, '10')

INSERT INTO #DEMO1 (a.a.a.value1,b.b.b.value2)
    SELECT
        Value1, Value2
    FROM #DEMO

If you see the insert statement, I have specified some alias name in the inserted columns. To my wonder, SQL Server didn't throw any error while executing the statement. What's the reason behind this? Could anyone help?