Why is TCP receive window a multiple of MSS?

Question

Why is TCP receive window considered to be a multiple of MSS Maximum Segment Size?

Wiki states that in order to fully utilize the packet lengths and avoid IP fragmentation , an integral multiple of the Maximum Segment Size (MSS) is generally recommended for the receive window and the value is therefore often only given as a factor/multiple.

Here it is stated that segments exceeding the MSS size is discarded.

Answer 1

For alignment... ergo it fits in a nic buffer on [ROM] @ a place in its memory which is then what you read from via a port or DMA