I get the logic that you cores wanna react to enemy support but doing so makes the enemy dictate your hero choice and make us support force pick the very boring supports like lion or cm instead of getting WW when enemy cores pick a physical heavy lineup or oracle or aba. Support choice matter too! We can counter cores too!
Not in all cases but if we pick heroes like winter wyvern, enemy would most likely go less physical and those that can also take advantage of cold embrace like mirana or od
I also get flamed if I want 2nd pick as pos4. Chances are, core player have a smaller hero pool they are very good in while support players can probably make us of more support heroes.
Lastly, it’s also good to know the picks of our cores beforehand so that we can pick synergystic heroes instead of having our cores pick heroes that match better with support picks…
Source: https://www.reddit.com/r/DotA2/comments/pax12c/ancient_tier_cores_why_always_make_pos4_and_5/