Laravel abstracted the PHP language enough that there are "Laravel developers" who cannot work without a framework. Now, these gems are going to do the same thing with HTML and Javascript!
These tools are contributing to the lowering of code quality standards, regardless of their intentions or the rigidity of their coding standards. They're good tools once you understand how they work, but most of its users use it precisely so they don't have to.
Productivity always has side effects, and usually that comes in the form of abstracting away the plumbing to "ship stuff".
For lots of working developers out there, "ship stuff" is their job, and you can't expect every single dev to understand the stack they work in end-to-end and to build their own plumbing each time, just for the sake of some ideal of knowledge.
It's a straw man to say that frameworks "lower code quality standards". I would argue in a lot of cases it's the opposite and they help codify best practices for the 80% of web applications that are the same, instead of everyone having their own custom implementations of templating, event handling, auth, caching, etc...
Would you rather have journeyman programmers building crappy templates and inefficient controller logic, or crappy auth systems and slow storage layers?
Frameworks provide guard rails and let less skilled developers be more productive as they get better over time. One can hope that some will dig in under the hood to learn more, but if they don't, so be it. At least they're not building your auth system or rolling their own hashing libraries.
If you need to understand deeply how all your tools work to use them, they are not good tools. They serve to abstract knowledge into them. Can you imagine if you needed to understand exactly how a computer does math in order to use Excel?
These tools are contributing to the lowering of code quality standards, regardless of their intentions or the rigidity of their coding standards. They're good tools once you understand how they work, but most of its users use it precisely so they don't have to.