It's not unique to tech, but it's necessary for funds of this size. Let's say Andrew's entire fund is made up of $5m investors. That means he has to close at least 30 investors, which means he probably has to pitch 60-90. Not only that, but actively maintaining 30 relationships and making sure they are effectively informed of the funds progress is difficult and time consuming as well. Andrew's time is probably best spent working with portfolio companies on their tech, so the less time he has to spend courting and showing love to LP's the better.

That's why they limit investment size. It's not to be purposefully exclusionary, they just have to be mindful of efficient use of time.