I suppose a self quote will do, despite having said yourself that
"Having said that
what's the use of saying 'ground of being' or 'source'?
Since nothing has ever existed as ground of being or source
these are simply totally useless thoughts.
Plain and simple."
The approach to simplicity you describe, there is a Gatha:
Taken from the Plumb Village website:
"Originally, there is no Bodhi tree
The bright mirror does not exist either
From the non-beginning of time nothing has ever existed
So where can the dust settle?"
We can say:
“A white cloud passes by and hides the mouth of the cave
Causing so many birds to lose their way home.”
Moving on....
Two stories, shared by Master Thay.
1
In the first story, the Zen master asked the novice monk:
“Tell me about your understanding of the Heart sutra.”
The novice monk joined his palms and replied:
“I have understood that the five skandhas are empty. There are no eyes, ears, nose, tongue, body or mind; there are no forms, sounds, smells, tastes, feelings, or objects of mind; the six consciousnesses do not exist, the eighteen realms of phenomena do not exist, the twelve links of dependent arising do not exist, and even wisdom and attainment do not exist.”
“Do you believe what it says?”
“Yes, I truly believe what it says.”
“Come closer to me,” the Zen master instructed the novice monk. When the novice monk drew near, the Zen master immediately used his thumb and index finger to pinch and twist the novice’s nose.
In great agony, the novice cried out “Teacher! You’re hurting me!” The Zen master looked at the novice. “Just now you said that the nose doesn’t exist. But if the nose doesn’t exist then what’s hurting?”
Second , the story of a Bhikkhu who came with a question to the Eminent Master Tue Trung.
2
The Eminent Master Tue Trung was a lay Zen master who had once served as the mentor for the young King Tran Nhan Tong, in 13th Century Vietnam. One day, a Bhikkhu paid him a visit to ask him about the Heart Sutra.
“Respected Eminent Master, what does the phrase ‘form is emptiness, emptiness is form,’ really mean?”
At first the Eminent Master remained silent. And then, after a while, he asked:
“Bhikkhu, do you have a body?”
“Yes, I do.”
“Then, why do you say that the body does not exist?”
The Eminent Master then continued, “Do you think that in empty space there is form?”
“No, I do not see that there is form.”
“Then why do you say that emptiness is form?”
The Bhikkhu stood up, bowed, and went on his way. But the Master summoned him back in order to recite to him the following gatha:
Form is emptiness, emptiness is form,
is a skillful means created temporarily by the Buddhas of the three times.
Emptiness is not form, form is not emptiness
Their nature is always pure and illuminating, neither caught in being nor in non-being.
I take further inspiration from the Master's insight and the article written with regards to his understanding:
From Plumb Village:
"The problem begins with the line: ‘Listen Shariputra, because in emptiness, there is no form, feelings, perceptions, mental formations, and consciousness’ (in Sanskrit: TasmācŚāriputraśūnyatayāmnarūpamnavedanānasamjñānasamskārānavijñānam). How funny! It was previously stated that emptiness is form, and form is emptiness, but now you say the opposite: there is only emptiness, there is no body. This line of the sutra can lead to many damaging misunderstandings."
My own thoughts:
I have read the heart Suttra's (prajnaparamita) classic English translation, meditated on it, and found that it was a vehicle to understanding duality and truth. I have felt the pull of Nihilistic thoughts but knew that they could not be the purpose in such wisdom because they have an obviously false nature. What you have written, by comparison, is an extreme view of "No self" and "Simplicity" when a proper view seems to me to be "no separate self" and "do not over complicate" . Everything is dependent and empty of a self, ideas, concepts, suffering all of it empty of self and separate nature. This is true. But it does not mean that being empty of a "self" or independent nature means that these things do not exist.
If it was a fact that emptiness, or void-ness was an absolute value and that all other things were truly without meaning or purpose then the novices nose would not hurt. If thoughts were useless and emptiness were perfectly true then knowing a car has no true nature and is empty, we could stand in front of it as it raced down the road. We all know that we cannot.
One of the things that Nihilistic or "Simplistic" logic does is that is tells us that there is no meaning, that all things are truly equal, that compassion and anger, kind and unkind, they have no separate value. You speak unkindly to people, and are provocative, I do not care how you write to me, I walk in fire all day, all you have are embers, but please, be kind to others. All beings deserve peace, I faced many beings whom others would argue with great fervor should be put to death and I deny it. The least you can do is make an attempt at being polite.
https://plumvillage.org/news/thich-nhat-hanh-new-heart-sutra-translation/ 
