Why AJAX+PHP not Flash+PHP??

[MooGeek]

As far as I can see, lots of Developer and Webmasters choose AJAX rather than Pure Flash Sites. and I've read lots of articles about this topic. but even them can't give me a concrete answer WHY would they choose AJAX rather a Full Flash site.

As far as I can see, these are the common problems why they would not Choose Pure Flash

1. Flash sites don't have direct URL
2. Google can't read them(but I heard that google is trying to read flash sites too now)
3. Bigger consumption on bandwidth
4. Flash needs to be done in a Software which is kinda expensive, unlike AJAX, just notepad
5. Or is it just the Open-Sourcesm??

now the 1. problem can be logically possible to do
3. but you can lower the bandwidth :(
4. that's a real problem most specially in companies. that's why Companies now are starting to use linux instead of window because its coming free now.

but using flash I think can do more and more powerful and good looking sites than AJAX right?? I mean it can almost do what a software can when it comes into GUI

now tell, why? :-/

[FlashCreations]

I think the question is not Flash/PHP vs. AJAX/PHP. Since Flash also designs content I would argue the debate is actually Flash vs. HTML5/CSS/JavaScript. The latter is an inseparable and pretty much unbeatable trio.
Besides the open source benefits of HTML, CSS, and JavaScript, the big seller for most font end developers and designers is that they are one-hundred percent free. Some don't have the $500 to drop on products from Adobe to develop Flash content for their site.
The other big reason for HTML/CSS/JavaScript over Flash in my mind is that HTML/AJAX/JavaScript has a fall back. AJAX (or JavaScript) is only meant to extend the experience of a static HTML page, so when it's not supported, the browser just falls back to links and static content contained in the HTML. Flash, on the other hand, has no easy fall back. If a user doesn't have Flash, they might see a message similar to Youtube's "Javascript is not enabled or you need to install Flash" message. To create a fall back for a fully Flash site you would need to code it in HTML/CSS, which defeats the purpose of creating it in Flash in the first place.

As I've made it quite obvious by now, I'm on the HTML/AJAX side of the argument, but there are some valid points for Flash. Currently, there is no open source video format supported by HTML5 that includes live video or audio, so until the day that becomes available, sites like Justin.tv and UStream.tv will continue to use Flash.
Flash is also extremely useful for online games, and while they can be ported to HTML5/JavaScript, I think that Flash streamlines the game development process and provides a wealth of useful tools for creating characters and object interactions. JavaScript is a lack-luster language to begin with, and making game processing rely on it is just not feasible yet, but it might be soon.
Some chat applications and sites that require live interaction require the use of ports. WebSockets are becoming the standard for sockets on future forward browsers such as Safari, but a majority of internet users have a browser that doesn't support WebSockets (I'm looking at you IE). Flash can be (and is) used where WebSockets aren't supported. A small SWF at the bottom of a page can take commands from JavaScript and communicate through ports to other servers. This might change in the near future, but for now, Flash is widely used for that application.

To sum everything up, I'd argue for HTML/CSS/JavaScript just because it's what I know. It works almost everywhere a browser will work, and unlike Flash is completely free to develop. For the Flash Developers out there, HTML/CSS may be less familiar. In which case, it is acceptable use Flash for websites they develop. The whole Flash vs. HTML5/JavaScript debate comes down to one question in my mind: Which do you use more?

[MooGeek]

I'm into The Trio thing. since flash isn't opensource, plus its gonna be more complicated now if I use flash. I agree to all you said. specially on its availability as the software is not free. and its compatibility. since a simple site doesn't need a showy page just to impress its visitors, but more importantly it's simplicity and easy to use I guess. but yeah, Flash is the weapon in gaming industry. Good point!

[ApocDen]

if i were to choose i would choose Ajax+php mainly because of it usage and there are every few limitations. i have used both on a project and i have to say i would Ajax and php is a lot less simple.