Yes it's not that simple. Even today some anger management therapists will suggest that you hit a pillow or something to let your anger out. This is actually really bad because it links those feelings to getting physically angry - you're conditioning yourself to respond to anger with physical outbursts.
It's not at all clear that 'don't bottle them up' is generally good advice.
False dichotomy--there are other alternatives than lashing out physically or "bottling up" your feelings. "Bottling up" generally refers to going into denial and emotionally repressing yourself. Sometimes just sitting and thinking about something calmly helps. Sometimes distracting yourself, or creating distance can help. But pretending everything is okay doesn't seem to be a winning strategy.
Sometimes distracting yourself, or creating distance can help.
That sounds like 'bottling up' to me though? I think we agree in principle, I just don't think 'don't bottle up your feelings' is the best way to describe these strategies.
It's not at all clear that 'don't bottle them up' is generally good advice.