I understand that mobile is new territory, and that web applications have certain restrictions on them (though less and less so with modern standards and modern browsers), but it seems very strange to me that there are still such glaring disparities between the web, mobile, and desktop versions of some products - even products designed with mobile in mind.
Take Evernote as an example. It's been out for Android for ages, with regular new releases offering new features and functionality. Yet there are still basic features that are not available in the mobile client, including strike-through text, horizontal rules, alignment, and font face/size changes. If you have a note with these features, and you edit the note in the Android app, you get a friendly warning that the note contains unsupported features, and the editor forces you to edit paragraph-by-paragraph, like the old and irritating Google Docs app for Android. I find this more than a little bit ridiculous; why are you adding new, nice-to-have features when basic functionality is still unsupported?
Look at Google Keep for the opposite example. The mobile app allows reordering the items in a checklist with drag-and-drop. The web app doesn't allow you to reorder items. The only way to reorder items is using cut and paste. This is something you can absolutely achieve in a web app, and they've done it before, but for some reason that one, basic, important feature is just somehow missing.
The Mint mobile app allows changing budgets, but not changing whether or not the budget surplus/deficit should roll over month-to-month, which you can do in the web app. It's most of the feature, just missing one little part that can cause frustration because if most of the feature is there, you expect the whole feature to be there.
The GitHub web app doesn't even include a git client - the closest you can get is downloading a repo, but you can't actually check out and manage a working copy.
The Google Maps app for Android doesn't allow editing your "My Maps", or to choose from (or create) alternate routes when getting directions. It also doesn't include the web version's traffic forecasting. The Blogger web app is next to useless; editing a note created on the desktop gives you a WYSIWYG editor with the plain text littered with markup, and writing a post on mobile and then looking at it on desktop shows that there's some serious inconsistencies with handling of basic formatting elements like paragraphs. Don't even get me started on the useless bundle of bytes that is the Google Analytics Android app; it's such a pathetic shadow of the web application that there's no point in even having it installed.
These seem to me like cases of failure to eat your own dog food. If there were employees - especially developers or product managers - of these companies, using these applications on each supported platform, these issues would have been solved. They're the sorts of things that look small and insignificant on a backlog until they affect you on a day-to-day basis; those little annoyances, repeated often enough, become sources of frustration.