Size is no measure of sound teaching--if so Full Gospel Central Church in Seoul Korea(hundreds of thousands of members) would be the standard of the world--it has many doctrinal problems.
"Size is no measure of sound teaching"
Neither is smallness. Different churches have different attributes.
Some seeker churches have become large, but many have remained small or have disappeared due to the lack of sound doctrine. Many people will start out in a seeker friendly church and change to a different church with sound doctrine as their faith matures.
Spome people like big churches with sound doctrine. I am one of them.
One of the benefits I have found in my Megachurch is that it is full of Christian activists. Really high energy Christians, fully engaged in the outside world, bringing Jesus to those who have not yet seen His light.
Actually, the church refers to itself as "The Fellowship of Excitement". We (members) refer to it as "The Fellowship of Exhaustion".