SAP is an Enterprise Resource Planning (ERP) system by SAP AG, company based out of Walldorf in Germany. SAP software suite provides end to end solutions for financial, logistics, distribution, inventories. Present scenario large number of companies are using sap software for their day to day business activities.
Major Advantage of SAP
2. Customized solutions to suit your business.
3. Highly integrated with other modules.
4. Industry specific modules with a deep insight.
5. Continuous support.
The major advantages of sap erp, is the HIGHLY INTEGRATION WITH OTHER MODULES OF BUSINESS, which is not there in other SOFT WARES. In other software, you need to have different software's for different module.
Now lets come to your Question Why SAP in IT industry
SAP does not have IT industry specific solution (http://go.sap.com/solution.html#solutionsbyindustry ) however it has telecom and healthcare specific solution. So dont know how should I answer your query with specifics. Please comment if looking for something different -