Until then, display: table kept everyone calm.
With css grid, I can tell each element which area or column+row to occupy.
If I add or remove a random element, the rest of the elements stay in the correct place.
But do that with a table and you end up trying to glue your house back together shard by shard whilst trying not to cut yourself or breaking things more.
This complaint highlights how absurdly not fit-for-purpose html+css actually is. Okay, you may want to do "responsive" design, but you have the semantic layout fixed, therefore you try and contort a styling engine into pretending to be a layout engine when in reality it is three stylesheets in a trenchoat.
I need to write this up properly, but one of my bugbears with responsive design is that it became normalised to push the sidebar down below the content on small screens. And if you didn't have a sidebar, to interweave everything in the content no matter what screensize you were viewing on.
What I want is a way to interleave content and asides on small screens, and pull them out into 1+ other regions on larger screens. Reordering the content on larger screens would be the icing on the cake but for now I'll take just doing it.
This CSS Grid approach adds gaps: https://codepen.io/pbowyer/pen/azNarbZ
Using named grid-template-areas stacks the items you move to the sidebar on top of each other, so you only see one of them.
'Good' old floats get most of the way, but put the item in the sidebar exactly where it falls. Plus they're a pain to work with overall: https://codepen.io/pbowyer/pen/jEqdJgP
this not fit for purpose may in fact be historically superseded usages that still are baked in to some usages affected by the relatively rapid change of the various platforms that must interact and use the respective technologies, the specification version of "technical debt"
that is to say some subsets of the numerous technologies can be used to construct something fit for the purpose that you are describing, but as a general rule anything constructed in a solution will probably be using other subsets not fit for that particular purpose, but maybe fit for some other purpose.