Can we delete confusing feature about inline-config command line option?

[ganmacs]

Is your feature request related to a problem? Please describe.

#2708

I hadn't use this this feature until now.
I got confused about this feature.

I expected that inline config is freshly and entirely used for Fluentd configuration.
However, currently, inline config is appended loaded Fluentd configuration.

This behavior got confuse for me.

Describe the solution you'd like

Just deleting the feature which reads an additional config from STDIN when passing the value - as inline-config command-line option to fluentd.

Describe alternatives you've considered

Additional context

Are there any backgrounds about this feature? @repeatedly