What's the purpose of slipping the first stitch on every row

I am working an Oat Couture pattern for a baby blanket. Every single row starts with a slip stitch purlwise. Is there a reason as to why this is? Does it do something special?

Was just curious.

Thanks

It pulls the stitch across 2 rows, making a nice, neat edge.

I think it makes seaming easier too.

On the baby blanket, the purpose is to produce a more finished looking edge.