There are some things included in SSIS that it would be foolish to re-implement in T-SQL. However, if you consider the Windows Batch commands that can be issued via xp_cmdshell and the .NET code that can be implemented in SQLCLR modules part of T-SQL, and you overlook some aspects of securing SQL Server with respect to enabling those features in your instance then yes, you can do everything in T-SQL that you can do in SSIS.