Why cant I add my own intermidate operation

[Boaz Nahum]

Many and I asked before how can I do that and that (for example producing
stream of parser tokens from stream, that cant be done by #collect, because
we have no way to know where the input stream is ended)

I understand that not any wish can be satisfied.

But why not provide a tiny  'gate' to add my pipeline, something like
already done:

 public <E_NEXT, S_NEXT extends BaseStream<E_NEXT, S_NEXT>> S_NEXT
pipeline(IntermediateOp<E_OUT, E_NEXT> newOp) {

That all I need(I know I can do there many mistakes, write it
inefficient,but still it is better than nothing).

Today I need to break the pipeline (at least syntactically)

My feeling is that 'Stream' is so difficult to extend. Why *so many
interfaces such as IntermediateOp* and TerminalOp are  not public ?

Thanks
Boaz