Question about high level support players early game items.

Not starting items but, for example: the play “y’” on a couple replays I watched of him playing vengeful spirit would go a wraith band to start, resupply some tangoes and mangoes, then would finish a second wraith band before boots or wand or anything.

As the legend 3 pleb I am, I just wonder his mindset behind this. Is he wanted to be more survivable because of the stats, so more harass damage? I just don’t see the main point over getting 2 wraithbands instead of finishing your wand or raindrops.

I’m sure it’s matchup dependent but he was laning with a sniper against Pudge and Lion, so I was just curious if anyone could help me understand.