Search for a WYSIWYG, non-latex Online collaborative paper writing Tool Is there a tool that is


WYSIWYG and not latex (in fact any coding) base
online (for ease of collaboration)
Can write math equation
Does line numbering
Does equation numbering


Google Doc is perfect for 1-3, but they don't support 4-5 (unless you work around by using tables, but that's not really a nice solution)

Authorea and Overleaf does 2-5, but is very latex/code based. (Despite Overleaf's rich text editing mode, which is a step closer to what I want, but still quite far from the goal)

(At the moment, I am just using Google Doc and do all the numbering post exporting to .doc)

---------This is not the same question as Collaborative paper-writing with non-LaTeX-using colleagues------------

Reasons:


The author of that question clearly wants to use latex for his part of the collaboration, but wants a non-latex front end for his no-latex using collaborators. Unlike him, apart from writing equations, I have absolutely no intention of using any latex code. In fact, I will be satisfied with MS word type equation editor (as long as it lets me put equation number on it)
The accepted solution to that post includes solution like overleaf and Authorea, which I specifically said is not satisfactory to me because they are too latex based.
Another population solution to that post was Lyx, which clearly fails the 'Online' part of my question.


At risk of repeating myself, let me say this. That post is after a masked latex service. Whereas I am after a Google Doc with line and equation numbering feature. If I insert a table, I want to insert a table, not a \begin{tabulate\table} environment, if I insert of picture, I want to be able to drag and adjust its position. I want a truly WYSIWYG editor.
Considering all of your requirements, I would suggest the following solutions, all of which essentially are either based, or focused on (compatible with) using Microsoft Office 365 software:


Microsoft Office Equation Editor (see this, this and this);
Microsoft Mathematics Add-in (in the context of this question, Microsoft Mathematics software provides an extended collection of symbols and structures for mathematical expressions; see this page for more details);
MathType by Design Science (this is the most comprehensive solution, which is compatible with Office 365 environment, among many others; in fact, Microsoft Office Equation Editor is a simplified version of MathType).