OK, I figured it out.
Assuming you are customizing a template clone extension, removing the Star Rating system from AbanteCart while keeping the written Review system requires 1 core edit plus 3 extension edits:
1 - (Core edit) - go to sitename/storefront/controller/responses/product/review.php. Comment out lines 121-123:
// if (!$this->request->post['rating']) {
// $this->error['message'] = $this->language->get('error_rating');
// }
This halts the validation process for the Star Rating element of the Product Review system. If it is no longer validated, it is no longer required to be displayed.
2 - In sitename/extensions/mytemplate/storefront/view/mytempate/template/pages/product/product.tpl - comment out lines 340-345:
[code[<!-- <div class="form-inline">
<label class="control-label col-md-3 pull-left"><?php echo $entry_rating; ?>
<span
class="red">*</span></label>
<?php echo $rating_element; ?>
</div> -->[/code]
The removes the Star Rating element from the Product Review element under the Review tab on the Product page.
3 - add to style.css : #current_reviews.mb20 .content img {display: none;}
This hides the individual Star rating displayed next to the name of each prior reviewer.
4 - add to style.css: .productprice .rate {display: none;}
This hides the Stars that are displayed on the product page.
PS - if you want to remove the | character that is displayed after the reviewer Name: delete it from line 3 of your template/responses/product/review.tpl.
This is my thinking:
The star ratings system includes a numerical calculation of the average of Star Ratings for each product, with the resultant display of the calculated numerical average rating, in terms of stars, on each Product page. On a new site with no ratings of any product, there are no errors associated with the absence of ratings on which to perform the calculations. If a site admin removes the coded validation for the required Product Review Star Rating element, the system will not generate an error if the customer does not select a star rating. If the site admin then removes or hides all Star Rating entry points on the front end, there will never be any Star Rating values entered by a customer. In this sense, the site will remain in a perpetually 'new" state with no Rating data, which should mean that the Average Star Rating calculation system will not lead to future errors. As such, no other editing of core files should be necessary to disable the Star Rating system. All you need to do is make some edits in your template extension to remove displayed elements of the Star Rating system.
If I missed anything crucial, hopefully an AC staff member will jump in to tell me how my site will eventually break.
Thx.
PPS - steps 3 and 4 may not be essential. I don't have time to go back and test, but theoretically, there is no need to hide an item that will never be displayed because of the step 2 removal of the entry point for that item's source data.