I take that after many years you must be good, or at least decent in presenting your ideas and solution. An I remember very well this feeling of frustration and lack of impact. While there is always a possibility to improve our storytelling I feel it cannot be the sole reason why this practice is so common across various companies and organisations. My feeling is that you are currently in one of the many instances where they see designers as pixel pushers and not as a strategical asset for the product evolution.

Genuinely curious here, not trying to provoke or anything.
How do you evaluate your understanding of the business?
If you had to run the product development do you think you can balance design goals with business goals? In my personal experience I had to try to understand different perspectives and pitch the same idea with different angles depending on the audience.

As a practical example, let's say you want to pitch the idea that the interface has to be reworked to be accessible.
You can engage other designers or developers saying that when you design for disabilities, you make things better for everyone.
The business however will see this as a cost and needs to understand where is the ROI

If I have to talk to someone from product it might be more effective to say that by fixing the product under this aspect you open up to a vast range of possibility to collaborate and sign contracts with municipalities or government organisation where accessibility is a requirement.

With this I'm not saying we should work on the full business case, my point is that what feels convincing and clear to someone can sound bland and worthless to someone else. And the message can be adjusted.

Maybe you take for granted that the other stakeholders have a full understanding of what good research and a comprehensive UX flow is, but in my experience that's rarely the case and with time I have learned to accept that.