This isnt always the case, I have always felt suspicious of ICOs when they link to the team members linkedin profile. Well, this may be legit in many cases as they want to build a positive trust by showing off the team. But, I also have seen people buying 20-25 old linkedin accounts through this forum.
This is quite right. If the team members are seemingly there, that's no guarantee the project is legit. They could be fake personas. Just look at the website of the fake
howeycoins ICO recently created by the Securities and Exchange Commission. The team seems to be listed (even though without Linkedin accounts or any other details), but of course the identities are fake.