It was fashionable.
In the ‘90s, I was routinely criticized for having caterpillars on my face. People told me they were “shocked” I didn’t pluck my eyebrows. The amount of shaming I dealt with for keeping my eyebrows thick was absurd; the implication was that I was unkempt and ugly because I had hair above my eyes. More than once, I was told they spoiled my whole face.
The particular irony of this was that I was self-conscious enough that I did pluck and shape my eyebrows, but I was very conservative about it, because I was aware that fashions change and that eyebrows don’t always grow back. I didn’t make any change I wasn’t prepared to live with forever.
Most people cave to social pressure more easily, both in forming their aesthetics and in conforming to the opinions of others.